draft-ietf-sipping-realtimefax-00.txt   draft-ietf-sipping-realtimefax-01.txt 
Internet Engineering Task Force Jean-Francois Mule SIPPING Working Group Jean-Francois Mule
Internet Draft CableLabs Internet Engineering Task Force CableLabs
Document: <draft-ietf-sipping-realtimefax-00.txt> Jieying Li Internet Draft
Category: Informational iVox Networks Document: draft-ietf-sipping-realtimefax-01.txt
Expires: February 2002 August 2002 Category: Informational Jieying Li
Expires: February 2003 August 2003
SIP Support for Real-time Fax: SIP Support for Real-time Fax:
Call Flow Examples Call Flow Examples
And And
Best Current Practices Best Current Practices
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1]. all provisions of Section 10 of RFC2026 [1].
skipping to change at line 53 skipping to change at line 54
fax mode, we briefly cover the fax pass-through mode to enable fax mode, we briefly cover the fax pass-through mode to enable
fallback operations and super G3 fax communications using SIP. We fallback operations and super G3 fax communications using SIP. We
also give examples of SIP call flows for real-time Internet fax also give examples of SIP call flows for real-time Internet fax
gateways or SIP proxy redirect servers. Elements in these call gateways or SIP proxy redirect servers. Elements in these call
flows include SIP User Agents, SIP Proxy Servers, and Gateways to flows include SIP User Agents, SIP Proxy Servers, and Gateways to
the PSTN (Public Switch Telephone Network). the PSTN (Public Switch Telephone Network).
This document introduces best current practices for SIP T.38 fax and This document introduces best current practices for SIP T.38 fax and
SIP fax pass-through sessions. A session starts with audio SIP fax pass-through sessions. A session starts with audio
capabilities, and, upon fax tone detection, T.38 fax capabilities capabilities, and, upon fax tone detection, T.38 fax capabilities
are negotiated; upon successful negotiation, the session continues are negotiated; upon successful negotiation, the session continues
with fax capabilities and the media termination hosts exchange T.38
Internet fax packets. The T.38 fax call scenarios include various
J-F. Mule/J. Li SIPPING WG 1 J-F. Mule/J. Li SIPPING WG 1
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
with fax capabilities and the media termination hosts exchange T.38
Internet fax packets. The T.38 fax call scenarios include various
aspects of the call sequence: the detection of fax transmission, the aspects of the call sequence: the detection of fax transmission, the
usage of the T.38 session description attributes, the optional usage of the T.38 session description attributes, the optional
fallback into fax pass-through mode and the session termination. The fallback into fax pass-through mode and the session termination. The
fax pass-through call scenarios involve some specific SDP media fax pass-through call scenarios involve some specific SDP media
attributes to enable proper fax transmission. attributes to enable proper fax transmission.
Fax transmission can be detected by the receiving side, the emitting Fax transmission can be detected by the receiving side, the emitting
side or both (in the latter case, a 'glare' effect may appear). side or both (in the latter case, a 'glare' effect may appear).
This document only covers the case when the fax transmission is This document only covers the case when the fax transmission is
detected by the receiving side: it is the most common practice and detected by the receiving side: it is the most common practice and
the other cases do not represent any particular challenges and are the other cases do not represent any particular challenges and are
therefore left for future discussions). Call flow diagrams and therefore left for future discussions). Call flow diagrams and
message details are shown. A list of IANA defined SDP attribute message details are shown. A list of IANA defined SDP attribute
names for T.38 is summarized in section 7. names for T.38 is summarized in section 7.
Table of Contents J-F. Mule/J. Li 2
SIP T.38 Call Flows February 2003
Status of this Memo.......................................................1 Table of Contents
1. Abstract...............................................................1
2. Conventions used in this document......................................3
3. Overview...............................................................3
3.1. General Assumptions.................................................3
3.2 Legend for Message Flows..............................................3
3.3 Changes to previous drafts............................................4
4 Handling of real-time fax communication using SIP.......................4
4.1 Internet telephony gateways and fax detection.........................5
4.2 Internet telephony gateways and T.38 fax media connections............5
4.3 SIP session and fax termination.......................................6
4.4 Internet telephony gateways and fax pass-through mode.................6
4.5 Responses to SIP OPTIONS request......................................7
4.6 Beyond Internet telephony gateways....................................7
5 Successful SIP T.38 fax Call Scenarios..................................7
5.1 Internet fax device Ż fax only support................................7
5.1.1 Sequence Diagram....................................................7
5.1.2 Message Details.....................................................8
5.2 SIP T.38 fax call Ż fax stream replaces voice stream.................13
5.2.1 Sequence Diagram...................................................13
5.2.2 Message Details....................................................15
5.3 SIP T.38 fax call Ż fax stream added to voice stream.................25
5.3.1 Sequence Diagram...................................................26
5.3.2 Message Details....................................................27
5.4 SIP T.38 fax call Ż fax stream forced to replace voice stream........37
5.4.1 Sequence Diagram...................................................37
5.4.2 Message Details....................................................37
6. Unsuccessful Scenarios................................................41
6.1. Unsuccessful T.38 fax scenario Ż no support for T.38................41
6.1.1. Sequence Diagram..................................................41
6.1.2. Message Details...................................................42
6.2. Unsuccessful T.38 fax scenario Ż 488/606 response & G.711 fallback..43
6.2.1. Sequence Diagram..................................................44
6.2.2. Message Details...................................................45
7. SDP Attribute Table for T.38 sessions.................................50
8. Considerations........................................................51
8.1. Level of requirements for Internet gateways.........................51
8.2. Negotiation of UDP ports for T.38 transmission......................51
J-F. Mule/J. Li 2 Status of this Memo...................................................1
SIP T.38 Call Flows February 2002 1. Abstract...........................................................1
2. Conventions used in this document..................................4
3. Overview...........................................................4
3.1. General Assumptions.............................................4
3.2 Legend for Message Flows..........................................4
3.3 Changes to previous drafts........................................5
4 Handling of real-time fax communication using SIP...................5
4.1 Internet telephony gateways and fax detection.....................6
4.2 Internet telephony gateways and T.38 fax media connections........6
4.3 SIP session and fax termination...................................7
4.4 Internet telephony gateways and fax pass-through mode.............7
4.5 Responses to SIP OPTIONS request..................................8
4.6 Beyond Internet telephony gateways................................8
5 Successful SIP T.38 fax Call Scenarios..............................8
5.1 Internet fax device - fax only support............................8
5.1.1 Sequence Diagram................................................8
5.1.2 Message Details.................................................9
5.2 SIP T.38 fax call -fax stream replaces voice stream..............14
5.2.1 Sequence Diagram...............................................15
5.2.2 Message Details................................................17
5.3 SIP T.38 fax call - fax stream added to voice stream.............26
5.3.1 Sequence Diagram...............................................27
5.3.2 Message Details................................................29
5.4 SIP T.38 fax call - fax stream forced to replace voice stream....38
5.4.1 Sequence Diagram...............................................39
5.4.2 Message Details................................................39
6. Unsuccessful Scenarios............................................42
6.1. Unsuccessful T.38 fax scenario - no support for T.38............42
6.1.1. Sequence Diagram..............................................42
6.1.2. Message Details...............................................43
6.2. Unsuccessful T.38 fax scenario -488/606 rsp & G.711 fallback....45
6.2.1. Sequence Diagram..............................................46
6.2.2. Message Details...............................................47
7. SDP Attribute Table for T.38 sessions.............................52
8. Considerations....................................................53
8.1. Level of requirements for Internet gateways.....................53
8.2. Negotiation of UDP ports for T.38 transmission..................53
8.3. Adding a fax stream to SIP session vs. Replacing audio stream...53
8.4. Adding text to make use of SIP OPTIONS: in progress in draft-02.53
8.5. Use of IP addresses in SDP connection information...............54
8.6. Unsuccessful scenario: 606 or 488...............................54
8.7. SIP re-INVITE or UPDATE?........................................54
9. Security Considerations...........................................54
10. References.......................................................54
11. Acknowledgments..................................................55
12. Author's Addresses...............................................55
Full Copyright Statement.............................................56
Acknowledgement......................................................56
8.3. Adding a fax stream to SIP session vs. Replacing audio stream.......51 J-F. Mule/J. Li 3
8.4. Adding text to make use of SIP OPTIONS: in progress in draft-02.....51 SIP T.38 Call Flows February 2003
8.5. Use of IP addresses in SDP connection information...................52
8.6. Unsuccessful scenario: 606 or 488...................................52
9. Security Considerations...............................................52
10. References...........................................................52
11. Acknowledgments......................................................53
12. Author's Addresses...................................................53
Full Copyright Statement.................................................53
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119 [2]. this document are to be interpreted as described in RFC-2119 [2].
3. Overview 3. Overview
The Session Initiation Protocol (SIP) is defined by RFC2543 [3] and The Session Initiation Protocol (SIP) is defined by RFC3261 [3] and
T.38 is the ITU-T Recommendation defining the procedures for real- T.38 is the ITU-T Recommendation defining the procedures for real-
time Group 3 facsimile communications over IP networks [4]. This time Group 3 facsimile communications over IP networks [4]. This
document deals with the handling of real-time fax communications document deals with the handling of real-time fax communications
using the SIP protocol for T.38 fax and fax pass-through modes. using the SIP protocol for T.38 fax and fax pass-through modes.
For T.38, this document deals primarily with one transport protocol For T.38, this document deals primarily with one transport protocol
for the media: T.38 over UDP/UDPTL; T.38 fax packet transport over for the media: T.38 over UDP/UDPTL; T.38 fax packet transport over
TCP using SIP session establishment can easily be extrapolated. TCP using SIP session establishment can easily be extrapolated.
These T.38 call flows were developed in the design of carrier-class These T.38 call flows were developed in the design of carrier-class
SIP Telephony products supporting voice and real-time fax traffic. SIP Telephony products supporting voice and real-time fax traffic.
It is the hope of the authors that this document will be useful for It is the hope of the authors that this document will be useful for
the SIP community, SIP implementors of T.38 fax products, designers. the SIP community, SIP implementors of T.38 fax products, designers.
Call flows shown in this document complement the main SIP call flow Call flows shown in this document complement the main SIP call flow
Internet-Draft [5]. These call flows are based on the current Internet-Draft [5]. These call flows are based on the current
version 2.0 of SIP in RFC2543[3], the ITU-T T.38 Amendment 2 [6] and version 2.0 of SIP in RFC3261[3], the ITU-T T.38 Amendment 2 [6] and
an ITU-T SG8 liaison to IANA. Note: IANA registration of the T.38 an ITU-T SG8 liaison to IANA. Note: IANA registration of the T.38
SDP attributes is currently a work in progress. SDP attributes is currently a work in progress.
3.1. General Assumptions 3.1. General Assumptions
Internet telephony gateways with T.38 support MAY pass various fax Internet telephony gateways with T.38 support MAY pass various fax
tones (T.30 CNG, CED, etc.) or flag sequence (like V.21 Preamble) in tones (T.30 CNG, CED, etc.) or flag sequence (like V.21 Preamble) in
the RTP audio streams before those tones or flag sequence are the RTP audio streams before those tones or flag sequence are
detected. Once detected by the DSP resources, T.38 fax-capable detected. Once detected by the DSP resources, T.38 fax-capable
devices switch from audio to fax mode and initiate a T.38 fax packet devices switch from audio to fax mode and initiate a T.38 fax packet
transmission. transmission.
These best current practices MAY apply to "Network Gateway", These best current practices MAY apply to "Network Gateway",
"Enterprise Gateway" and Internet-aware fax devices or terminals. "Enterprise Gateway" and Internet-aware fax devices or terminals.
3.2 Legend for Message Flows 3.2 Legend for Message Flows
J-F. Mule/J. Li 3
SIP T.38 Call Flows February 2002
The legend defined [5] also applies in this document. The legend defined [5] also applies in this document.
Dashed lines (---) represent control messages that are mandatory to Dashed lines (---) represent control messages that are mandatory to
the call scenario. These control messages can be SIP or PSTN the call scenario. These control messages can be SIP or PSTN
signaling. Double dashed lines (===) represent media paths between signaling. Double dashed lines (===) represent media paths between
network elements. Messages with parenthesis around name represent network elements. Messages with parenthesis around name represent
optional control messages. Messages are identified in the Figures optional control messages. Messages are identified in the Figures
as F1, F2, etc. This references the message details in the table as F1, F2, etc. This references the message details in the table
that follows the Figure. Comments in the message details are shown that follows the Figure. Comments in the message details are shown
in the following form: /* Comments. */ in the following form: /* Comments. */
J-F. Mule/J. Li 4
SIP T.38 Call Flows February 2003
3.3 Changes to previous drafts 3.3 Changes to previous drafts
o Changes to sipping-draft-01
The changes between the current draft and the expired sipping draft-
00 are:
- removed ecan which is a local param and removed all text
- started realignment with rfc3261 (tags, branch, Max-Forward):
this remains unfinished and it has not been proof-read; look
for more rigorous updates in the next draft
- realigned with T.38 recommendation from 3/2002
+ corrected T38FaxFillBitRemoval, T38FaxTranscodingMMR,
T38FaxTranscodingJBIG
- edits: updated reference section (to do: need to split it into
normative vs. informative)
o Changes to draft-01 o Changes to draft-01
The changes between the current draft and draft-01 are: The changes between the current draft and draft-01 are:
- Major updates: - Major updates:
+ additions based on SIPit fax testing event 8/2001: added + additions based on SIPit fax testing event 8/2001: added
text regarding the negotiation of T38MaxBitRate in 4.2, text regarding the negotiation of T38MaxBitRate in 4.2,
+ added more general text for the handling of real-time + added more general text for the handling of real-time
fax pass-through, fax pass-through,
+ added of echo cancellation & silence suppression SDP + added of echo cancellation & silence suppression SDP
attributes and usage recommendations in 6.2, attributes and usage recommendations in 6.2,
+ correction of the session version number in SDP when + correction of the session version number in SDP when
skipping to change at line 217 skipping to change at line 235
+ additions of new successful call flows in section 5 + additions of new successful call flows in section 5
+ additions of unsuccessful call flows in section 6 + additions of unsuccessful call flows in section 6
- Added Record-Route header, modified Cseq numbers, - Added Record-Route header, modified Cseq numbers,
- Added T38FaxMaxDatagram attribute in SDP and corrected - Added T38FaxMaxDatagram attribute in SDP and corrected
the sample value for T38FaxMaxBuffer, the sample value for T38FaxMaxBuffer,
- Minor editorial changes (e.g. removed references in Abstract). - Minor editorial changes (e.g. removed references in Abstract).
4 Handling of real-time fax communication using SIP 4 Handling of real-time fax communication using SIP
The handling of real-time fax sessions using SIP involves the The handling of real-time fax sessions using SIP involves the
initial session establishment, the modification or negotiation of initial session establishment, the modification or negotiation of
J-F. Mule/J. Li 5
SIP T.38 Call Flows February 2003
session capabilities upon fax detection, the optional fallback into session capabilities upon fax detection, the optional fallback into
fax pass-through mode and the session termination. fax pass-through mode and the session termination.
J-F. Mule/J. Li 4
SIP T.38 Call Flows February 2002
Some variants of these best current practices MAY apply depending on Some variants of these best current practices MAY apply depending on
the nature or the configuration of Internet telephony gateways. Two the nature or the configuration of Internet telephony gateways. Two
distinct cases are considered in this document: distinct cases are considered in this document:
o The Internet telephony gateway only supports T.38 real-time o The Internet telephony gateway only supports T.38 real-time
fax communications (by design or by configuration). In this case, fax communications (by design or by configuration). In this case,
the Internet fax gateway SHOULD initiate the SIP session with T.38 the Internet fax gateway SHOULD initiate the SIP session with T.38
SDP capabilities (this is typically the case of Internet fax SDP capabilities (this is typically the case of Internet fax
terminals, also called Internet-aware fax devices or the case of terminals, also called Internet-aware fax devices or the case of
gateways statically configured to support T.38 fax calls only); gateways statically configured to support T.38 fax calls only);
o The Internet telephony gateway supports voice and real-time o The Internet telephony gateway supports voice and real-time
skipping to change at line 271 skipping to change at line 290
4.2 Internet telephony gateways and T.38 fax media connections 4.2 Internet telephony gateways and T.38 fax media connections
Upon successful fax detection, the description of the media Upon successful fax detection, the description of the media
connection(s) is modified using the SDP protocol [8] as described in connection(s) is modified using the SDP protocol [8] as described in
SIP (see sections in chapter 5). SIP (see sections in chapter 5).
Several cases should be considered: Several cases should be considered:
- In the case of Internet fax devices (supporting T.38 fax only - In the case of Internet fax devices (supporting T.38 fax only
communications), the SIP session is established with SDP description communications), the SIP session is established with SDP description
containing the T.38 media attributes; refer to section 5.1 for a
sample call flow for Internet fax devices.
J-F. Mule/J. Li 5 J-F. Mule/J. Li 6
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
containing the T.38 media attributes; refer to section 5.1 for a
sample call flow for Internet fax devices.
- In the case of Internet telephony gateways, the SIP/SDP session is - In the case of Internet telephony gateways, the SIP/SDP session is
modified and the T.38 fax media connection SHOULD replace the modified and the T.38 fax media connection SHOULD replace the
existing audio media connection. The SIP UAC triggering the existing audio media connection. The SIP UAC triggering the
modification of the session description MUST indicate all of its modification of the session description MUST indicate all of its
T.38 media attributes in SDP. This is the recommended behavior for T.38 media attributes in SDP. This is the recommended behavior for
gateways; refer to section 5.2 for a sample call flow illustrating gateways; refer to section 5.2 for a sample call flow illustrating
this scenario. this scenario.
Some implementations MAY choose to add the fax media connection to Some implementations MAY choose to add the fax media connection to
the existing audio connection and in that case, they SHOULD mute the the existing audio connection and in that case, they SHOULD mute the
audio connection while fax is transmitted. Refer to section 5.3 for audio connection while fax is transmitted. Refer to section 5.3 for
skipping to change at line 325 skipping to change at line 344
The fax pass-through mode is important to prevent call failures, for The fax pass-through mode is important to prevent call failures, for
example in cases when one of the SIP communication peers does not example in cases when one of the SIP communication peers does not
support T.38. For Internet telephony gateways with support for support T.38. For Internet telephony gateways with support for
PCM/G.711 audio but no support for T.38 real-time fax, it is PCM/G.711 audio but no support for T.38 real-time fax, it is
recommended to switch the session to fax pass-through mode. recommended to switch the session to fax pass-through mode.
Internet telephony gateways SHOULD handle the fall back mode to fax Internet telephony gateways SHOULD handle the fall back mode to fax
pass-through by recognizing the SDP T.38 connection and proposing to pass-through by recognizing the SDP T.38 connection and proposing to
switch to a new audio connection. The new audio connection SHOULD switch to a new audio connection. The new audio connection SHOULD
have the following characteristics: at a minimum, specify PCM G.711 have the following characteristics: at a minimum, specify PCM G.711
codec, silence suppression OFF, echo cancellation ON. The telephony codec, silence suppression OFF. The telephony gateway that
gateway that originated the failed T.38 re-INVITE SHOULD initiate
the subsequent re-INVITE to fax pass-through mode.
J-F. Mule/J. Li 6 J-F. Mule/J. Li 7
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
originated the failed T.38 re-INVITE SHOULD initiate the subsequent
re-INVITE to fax pass-through mode.
Refer to section 6.2 for a sample call flow illustrating this Refer to section 6.2 for a sample call flow illustrating this
scenario. scenario.
4.5 Responses to SIP OPTIONS request 4.5 Responses to SIP OPTIONS request
Suggestion currently logged in section 8.4, just a placeholder for Suggestion currently logged in section 8.4, just a placeholder for
now; <<work in progress >> now; <<work in progress >>
4.6 Beyond Internet telephony gateways 4.6 Beyond Internet telephony gateways
This document may also serve to vendors of SIP redirect servers or This document may also serve to vendors of SIP redirect servers or
other SIP UA types like SIP phones. Such SIP entities may recognize other SIP UA types like SIP phones. Such SIP entities may recognize
the fax nature of the sessions and redirect the flows to the proper the fax nature of the sessions and redirect the flows to the proper
real-time fax-capable devices or to other fax service providers. real-time fax-capable devices or to other fax service providers.
5 Successful SIP T.38 fax Call Scenarios 5 Successful SIP T.38 fax Call Scenarios
5.1 Internet fax device Ż fax only support 5.1 Internet fax device - - fax only support
This section represents a SIP call flow for a T.38 fax session This section represents a SIP call flow for a T.38 fax session
between 2 Internet fax terminals. It is also applicable to Internet between 2 Internet fax terminals. It is also applicable to Internet
telephony gateways when telephony ports are statically configured to telephony gateways when telephony ports are statically configured to
support fax only (case of analog IP telephony gateways where a support fax only (case of analog IP telephony gateways where a
specific port is connected to a fax terminal). specific port is connected to a fax terminal).
A session starts with fax capabilities (t.38/udptl). The mechanism A session starts with fax capabilities (t.38/udptl). The mechanism
for supporting T.38 in SIP & SDP is detailed in T.38 Annex D [9], a for supporting T.38 in SIP & SDP is detailed in T.38 Annex D [9], a
temporary document that proposes an amendment to T.38 describing SIP temporary document that proposes an amendment to T.38 describing SIP
call establishment procedures. call establishment procedures.
skipping to change at line 377 skipping to change at line 396
| | F2 INVITE | | | F2 INVITE |
| |------------------->| | |------------------->|
| F3 100 Trying | | | F3 100 Trying | |
|<-------------------| F4 100 Trying | |<-------------------| F4 100 Trying |
| |<-------------------| | |<-------------------|
| | | | | |
| | F5 180 Ringing | | | F5 180 Ringing |
| F6 180 Ringing |<-------------------| | F6 180 Ringing |<-------------------|
|<-------------------| | |<-------------------| |
| | F7 200 OK | | | F7 200 OK |
| F8 200 OK |<-------------------|
|<-------------------| |
J-F. Mule/J. Li 7 J-F. Mule/J. Li 8
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
| F8 200 OK |<-------------------|
|<-------------------| |
| F9 ACK | | | F9 ACK | |
|------------------->| F10 ACK | |------------------->| F10 ACK |
| |------------------->| | |------------------->|
| | | |
| T.38/UDPTL Fax Flow Established | | T.38/UDPTL Fax Flow Established |
|<=======================================>| |<=======================================>|
End of | | End of | |
fax | | | fax | | |
detected| | | detected| | |
------->| | | ------->| | |
skipping to change at line 406 skipping to change at line 425
| |------------------->| | |------------------->|
| | F13 200 OK | | | F13 200 OK |
| |<-------------------| | |<-------------------|
| F14 200 OK | | | F14 200 OK | |
|<-------------------| | |<-------------------| |
5.1.2 Message Details 5.1.2 Message Details
F1 INVITE I.FAX UA -> PROXY F1 INVITE I.FAX UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab111 Max-Forwards: 70
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ifax.here.com> Contact: <sip:+1-303-555-1111@ifax.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=ifaxgw1 2890846527 2890846527 IN IP4 ifax.here.com o=ifaxgw1 2890846527 2890846527 IN IP4 ifax.here.com
s=Session SDP s=Session SDP
c=IN IP4 ifaxmg.here.com c=IN IP4 ifaxmg.here.com
t=0 0 t=0 0
m=image 15002 udptl t38 m=image 15002 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
J-F. Mule/J. Li 8 J-F. Mule/J. Li 9
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
F2 INVITE PROXY -> IFTGW UA F2 INVITE PROXY -> IFTGW UA
INVITE sip:+1-650-555-2222@iftgw.there.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@iftgw.there.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab111 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ifax.here.com> Contact: <sip:+1-303-555-1111@ifax.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=ifaxgw1 2890846527 2890846527 IN IP4 ifax.here.com o=ifaxgw1 2890846527 2890846527 IN IP4 ifax.here.com
s=Session SDP s=Session SDP
c=IN IP4 ifaxmg.here.com c=IN IP4 ifaxmg.here.com
t=0 0 t=0 0
m=image 15002 udptl t38 m=image 15002 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F3 (100 Trying) PROXY -> I.FAX UA F3 (100 Trying) PROXY -> I.FAX UA
SIP/2.0 100 Trying SIP/2.0 100 Trying
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab111 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Content-Length: 0 Content-Length: 0
F4 (100 Trying) IFTGW UA -> PROXY F4 (100 Trying) IFTGW UA -> PROXY
SIP/2.0 100 Trying SIP/2.0 100 Trying
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11
J-F. Mule/J. Li 9 J-F. Mule/J. Li 10
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
F5 180 Ringing IFTGW UA -> PROXY F5 180 Ringing IFTGW UA -> PROXY
SIP/2.0 180 Ringing SIP/2.0 180 Ringing
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
F6 180 Ringing PROXY -> I.FAX UA F6 180 Ringing PROXY -> I.FAX UA
SIP/2.0 180 Ringing SIP/2.0 180 Ringing
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
F7 200 OK IFTGW UA -> PROXY F7 200 OK IFTGW UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
J-F. Mule/J. Li 11
SIP T.38 Call Flows February 2003
o=faxgw1 2890844527 2890844527 IN IP4 iftgw.there.com o=faxgw1 2890844527 2890844527 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=image 49172 udptl t38 m=image 49172 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
J-F. Mule/J. Li 10
SIP T.38 Call Flows February 2002
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F8 200 OK PROXY -> I.FAX UA F8 200 OK PROXY -> I.FAX UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 2890844527 IN IP4 iftgw.there.com o=faxgw1 2890844527 2890844527 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=image 49172 udptl t38 m=image 49172 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F9 ACK I.FAX UA -> PROXY F9 ACK I.FAX UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Max-Forwards: 70
Route: <sip:+1-650-555-2222@iftgw.there.com; Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 ;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
J-F. Mule/J. Li 12
SIP T.38 Call Flows February 2003
CSeq: 17 ACK CSeq: 17 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 11
SIP T.38 Call Flows February 2002
F10 ACK PROXY -> IFTGW UA F10 ACK PROXY -> IFTGW UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Max-Forwards: 69
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@iftgw.there.com;
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab11 maddr=obelix.banyuls.com>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
;tag=ab111
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 17 ACK CSeq: 17 ACK
Content-Length: 0 Content-Length: 0
/* T.38 fax streams are established. */ /* T.38 fax streams are established. */
F11 BYE I.FAX UA -> PROXY F11 BYE I.FAX UA -> PROXY
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab22 maddr=obelix.banyuls.com>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
;tag=ab22
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
;tag=cde34
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 18 BYE CSeq: 18 BYE
Content-Length: 0 Content-Length: 0
F12 BYE PROXY -> IFTGW UA F12 BYE PROXY -> IFTGW UA
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab22 maddr=obelix.banyuls.com>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
;tag=ab22
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
;tag=cde34
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 18 BYE CSeq: 18 BYE
J-F. Mule/J. Li 13
SIP T.38 Call Flows February 2003
Content-Length: 0 Content-Length: 0
F13 200 OK IFTGW UA -> PROXY F13 200 OK IFTGW UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab22 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
;tag=ab22
J-F. Mule/J. Li 12 To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
SIP T.38 Call Flows February 2002 ;tag=cde34
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 18 BYE CSeq: 18 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
F14 200 OK PROXY -> I.FAX UA F14 200 OK PROXY -> I.FAX UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ifax.here.com:5060 Via: SIP/2.0/UDP ifax.here.com:5060;branch=z9hG4bK74bf9
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ifax.here.com;user=phone;tag=ab22 From: iFax <sip:+1-303-555-1111@ifax.here.com;user=phone>
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 ;tag=ab22
To: fax Bob <sip:+1-650-555-2222@obelix.banyuls.com;user=phone>
;tag=cde34
Call-ID: 1717@ifax.here.com Call-ID: 1717@ifax.here.com
CSeq: 18 BYE CSeq: 18 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
5.2 SIP T.38 fax call Ż fax stream replaces voice stream 5.2 SIP T.38 fax call - - fax stream replaces voice stream
This section represents the SIP call flow for a T.38 fax session This section represents the SIP call flow for a T.38 fax session
between 2 Internet telephony gateways (fax detection on terminating between 2 Internet telephony gateways (fax detection on terminating
side). side).
A session starts with audio capabilities, and then the session is A session starts with audio capabilities, and then the session is
modified to switch to t38 fax mode (t.38/udptl). modified to switch to t38 fax mode (t.38/udptl).
Scenario: Scenario:
1. A SIP INVITE is sent to the called party requesting a voice 1. A SIP INVITE is sent to the called party requesting a voice
connection per RFC2543; our scenario involves 1 SIP proxy. An audio connection per RFC3261; our scenario involves 1 SIP proxy. An audio
connection is established, connection is established,
2. Upon detection of Preamble by the terminating gateway, a SIP re- 2. Upon detection of Preamble by the terminating gateway, a SIP re-
INVITE request is sent to the emitting gateway to modify the INVITE request is sent to the emitting gateway to modify the
parameters of the session to allow a T.38 fax media connection. parameters of the session to allow a T.38 fax media connection.
J-F. Mule/J. Li 14
SIP T.38 Call Flows February 2003
This INVITE request contains new SDP information detailing T.38 This INVITE request contains new SDP information detailing T.38
capabilities, capabilities,
3. Upon successful acknowledgments, T.38 IFP fax packets are 3. Upon successful acknowledgments, T.38 IFP fax packets are
sent/received on UDP ports, which may be the same UDP ports used for sent/received on UDP ports, which may be the same UDP ports used for
audio RTP, audio RTP,
4. Once the fax transmission is terminated, audio capabilities are 4. Once the fax transmission is terminated, audio capabilities are
ŰrestoredŲ or the call is terminated. śśrestored∆∆ or the call is terminated.
5.2.1 Sequence Diagram 5.2.1 Sequence Diagram
In our example, we illustrate the fact that Internet telephony In our example, we illustrate the fact that Internet telephony
gateways may use multiple network interfaces for signaling and/or gateways may use multiple network interfaces for signaling and/or
media streaming or one network interface with multiple IP addresses. media streaming or one network interface with multiple IP addresses.
Typically, our example shows: Typically, our example shows:
J-F. Mule/J. Li 13
SIP T.38 Call Flows February 2002
- one interface for SIP signaling - one interface for SIP signaling
(ingress gateway = ift.here.com, egress gateway = iftgw.there.com) (ingress gateway = ift.here.com, egress gateway = iftgw.there.com)
- one or multiple interface(s) for media transport: - one or multiple interface(s) for media transport:
(ingress gateway = iftmg.here.com, egress gateway = iftmg.there.com) (ingress gateway = iftmg.here.com, egress gateway = iftmg.there.com)
A proxy is acting as a pure SIP signaling proxy (obelix.wcom.com). A proxy is acting as a pure SIP signaling proxy
(obelix.banyuls.com).
IFT UA Proxy IFTGW UA IFT UA Proxy IFTGW UA
| | | | | |
| F1 INVITE | | | F1 INVITE | |
|------------------->| | |------------------->| |
| | F2 INVITE | | | F2 INVITE |
| |------------------->| | |------------------->|
| F3 100 Trying | | | F3 100 Trying | |
|<-------------------| F4 100 Trying | |<-------------------| F4 100 Trying |
| |<-------------------| | |<-------------------|
skipping to change at line 731 skipping to change at line 764
| ------------------->| | ------------------->|
| | | |
| Both Way RTP Media Established | | Both Way RTP Media Established |
Fax |<=======================================>| Fax |<=======================================>|
------->| | ------->| |
emitted | | | emitted | | |
| | | Preamble | | | Preamble
| | |<--------- | | |<---------
| | F11 INVITE | detected | | F11 INVITE | detected
| |<-------------------| | |<-------------------|
J-F. Mule/J. Li 15
SIP T.38 Call Flows February 2003
| F12 INVITE | | | F12 INVITE | |
|<-------------------| | |<-------------------| |
| | | | | |
| F13 200 OK | | | F13 200 OK | |
|------------------->| | |------------------->| |
| | F14 200 OK | | | F14 200 OK |
| |------------------->| | |------------------->|
| | | | | |
| | F15 ACK | | | F15 ACK |
| |<-------------------| | |<-------------------|
| F16 ACK | | | F16 ACK | |
|<-------------------| | |<-------------------| |
| | | |
| T.38/UDPT Fax Flow Established | | T.38/UDPT Fax Flow Established |
|<=======================================>| |<=======================================>|
End of | | End of | |
fax | | | fax | | |
J-F. Mule/J. Li 14
SIP T.38 Call Flows February 2002
detected| | | detected| | |
------->| | | ------->| | |
| | | End of fax | | | End of fax
| | |<---------- | | |<----------
| | | detected | | | detected
| | F17 INVITE | | | F17 INVITE |
| |<-------------------| | |<-------------------|
| F18 INVITE | | | F18 INVITE | |
|<-------------------| | |<-------------------| |
skipping to change at line 785 skipping to change at line 818
| F23 BYE | | | F23 BYE | |
|------------------->| | |------------------->| |
| | F24 BYE | | | F24 BYE |
| |------------------->| | |------------------->|
| | | | | |
| | F25 200 OK | | | F25 200 OK |
| |<-------------------| | |<-------------------|
| F26 200 OK | | | F26 200 OK | |
|<-------------------| | |<-------------------| |
J-F. Mule/J. Li 16
SIP T.38 Call Flows February 2003
5.2.2 Message Details 5.2.2 Message Details
<< NOTE: WIP - ALIGNMENT with RFC3261 req. incomplete for the rest
of the document.>>
F1 INVITE IFT UA -> PROXY F1 INVITE IFT UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 70
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 146 Content-Length: 146
v=0 v=0
o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
J-F. Mule/J. Li 15
SIP T.38 Call Flows February 2002
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F2 INVITE PROXY -> IFTGW UA F2 INVITE PROXY -> IFTGW UA
INVITE sip:+1-650-555-2222@iftgw.there.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@iftgw.there.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 146 Content-Length: 146
v=0 v=0
o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F3 (100 Trying) PROXY -> IFT UA F3 (100 Trying) PROXY -> IFT UA
J-F. Mule/J. Li 17
SIP T.38 Call Flows February 2003
SIP/2.0 100 Trying SIP/2.0 100 Trying
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Content-Length: 0 Content-Length: 0
F4 100 Trying IFTGW UA -> PROXY F4 100 Trying IFTGW UA -> PROXY
SIP/2.0 100 Trying SIP/2.0 100 Trying
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 16
SIP T.38 Call Flows February 2002
F5 180 Ringing IFTGW UA -> PROXY F5 180 Ringing IFTGW UA -> PROXY
SIP/2.0 180 Ringing SIP/2.0 180 Ringing
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
F6 180 Ringing PROXY -> IFT UA F6 180 Ringing PROXY -> IFT UA
SIP/2.0 180 Ringing SIP/2.0 180 Ringing
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
F7 200 OK IFTGW UA -> PROXY F7 200 OK IFTGW UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
J-F. Mule/J. Li 18
SIP T.38 Call Flows February 2003
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F8 200 OK PROXY -> IFT UA F8 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.banyuls.com>
J-F. Mule/J. Li 17
SIP T.38 Call Flows February 2002
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F9 ACK IFT UA -> PROXY F9 ACK IFT UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 70
Route: <sip:+1-650-555-2222@iftgw.there.com; Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 ACK CSeq: 17 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 19
SIP T.38 Call Flows February 2003
F10 ACK PROXY -> IFTGW UA F10 ACK PROXY -> IFTGW UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 ACK CSeq: 17 ACK
Content-Length: 0 Content-Length: 0
/* RTP streams are established. The CNG fax tone is sent in-band if /* RTP streams are established. The CNG fax tone is sent in-band if
it is present. The receiving side IFT gateway DSP detects the it is present. The receiving side IFT gateway DSP detects the
Preamble sequence. A new UDP port is open on IFTGW for T.38 IFP Preamble sequence. A new UDP port is open on IFTGW for T.38 IFP
packets and the IFTGW signals the switch over to fax mode by send a packets and the IFTGW signals the switch over to fax mode by send a
re-INVITE with the new UDP port in the SDP. re-INVITE with the new UDP port in the SDP.
J-F. Mule/J. Li 18
SIP T.38 Call Flows February 2002
Note: the IFTGW has a T38MaxBitRate configured to 9600 */ Note: the IFTGW has a T38MaxBitRate configured to 9600 */
F11 INVITE IFTGW UA -> PROXY F11 INVITE IFTGW UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=image 49172 udptl t38 m=image 49172 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:9600 a=T38MaxBitRate:9600
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
J-F. Mule/J. Li 20
SIP T.38 Call Flows February 2003
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F12 INVITE PROXY -> IFT UA F12 INVITE PROXY -> IFT UA
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
J-F. Mule/J. Li 19
SIP T.38 Call Flows February 2002
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=image 49172 udptl t38 m=image 49172 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:9600 a=T38MaxBitRate:9600
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
/* Note: the IFT has a T38MaxBitRate configured to 14400 but since /* Note: the IFT has a T38MaxBitRate configured to 14400 but since
it received a T38MaxBitRate proposal of 9600, it replies with it received a T38MaxBitRate proposal of 9600, it replies with
T38MaxBitRate = min (9600,14400) */ T38MaxBitRate = min (9600,14400) */
F13 200 OK IFT UA -> PROXY F13 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
J-F. Mule/J. Li 21
SIP T.38 Call Flows February 2003
o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=image 15002 udptl t38 m=image 15002 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:9600 a=T38MaxBitRate:9600
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F14 200 OK PROXY -> IFT UA F14 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
J-F. Mule/J. Li 20
SIP T.38 Call Flows February 2002
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=image 15002 udptl t38 m=image 15002 udptl t38
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:9600 a=T38MaxBitRate:9600
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F15 ACK IFTGW UA -> PROXY F15 ACK IFTGW UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 ACK CSeq: 18 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 22
SIP T.38 Call Flows February 2003
F16 ACK PROXY -> IFT UA F16 ACK PROXY -> IFT UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 ACK CSeq: 18 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 21
SIP T.38 Call Flows February 2002
/* T.38 fax transmission established both ways */ /* T.38 fax transmission established both ways */
/* Then, the end of the fax transmission is detected on ingress side /* Then, the end of the fax transmission is detected on ingress side
and sent to the egress side (IFTGW). IFTGW initiates the switch and sent to the egress side (IFTGW). IFTGW initiates the switch
back to voice communication */ back to voice communication */
F17 INVITE IFTGW UA -> PROXY F17 INVITE IFTGW UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 181 Content-Length: 181
v=0 v=0
o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F18 INVITE PROXY -> IFT UA F18 INVITE PROXY -> IFT UA
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com;
maddr=obelix.wcom.com> J-F. Mule/J. Li 23
SIP T.38 Call Flows February 2003
Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 181 Content-Length: 181
v=0 v=0
o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
J-F. Mule/J. Li 22
SIP T.38 Call Flows February 2002
F19 200 OK IFT UA -> PROXY F19 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F20 200 OK PROXY -> IFTGW UA F20 200 OK PROXY -> IFTGW UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
J-F. Mule/J. Li 24
SIP T.38 Call Flows February 2003
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F21 ACK IFTGW UA -> PROXY F21 ACK IFTGW UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
Route: <sip:+1-650-555-2222@obelix.banyuls.com;
J-F. Mule/J. Li 23 maddr=obelix.banyuls.com>
SIP T.38 Call Flows February 2002
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 ACK CSeq: 19 ACK
Content-Length: 0 Content-Length: 0
F22 ACK PROXY -> IFT UA F22 ACK PROXY -> IFT UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 ACK CSeq: 19 ACK
Content-Length: 0 Content-Length: 0
/* Voice streams re-established both ways */ /* Voice streams re-established both ways */
F23 BYE IFT UA -> PROXY F23 BYE IFT UA -> PROXY
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
J-F. Mule/J. Li 25
SIP T.38 Call Flows February 2003
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Length: 0 Content-Length: 0
F24 BYE PROXY -> IFTGW UA F24 BYE PROXY -> IFTGW UA
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Length: 0 Content-Length: 0
F25 200 OK IFTGW UA -> PROXY F25 200 OK IFTGW UA -> PROXY
J-F. Mule/J. Li 24
SIP T.38 Call Flows February 2002
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde24 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde24
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
F26 200 OK PROXY -> IFT UA F26 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde24 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde24
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
5.3 SIP T.38 fax call Ż fax stream added to voice stream 5.3 SIP T.38 fax call - - fax stream added to voice stream
J-F. Mule/J. Li 26
SIP T.38 Call Flows February 2003
This section represents the SIP call flow for a T.38 fax session This section represents the SIP call flow for a T.38 fax session
between 2 Internet telephony gateways. It shows the detection of between 2 Internet telephony gateways. It shows the detection of
the fax communication on terminating or receiving side. the fax communication on terminating or receiving side.
A session starts with one audio stream in SDP, and, upon detection A session starts with one audio stream in SDP, and, upon detection
of fax, an additional fax stream is added to the session while the of fax, an additional fax stream is added to the session while the
voice stream is muted. After the fax communication is terminated, voice stream is muted. After the fax communication is terminated,
the fax stream is terminated and the voice stream is restored. the fax stream is terminated and the voice stream is restored.
Scenario: Scenario:
1. A SIP INVITE is sent to the called party requesting a voice 1. A SIP INVITE is sent to the called party requesting a voice
connection per RFC2543; our scenario involves 1 SIP proxy. An audio connection per RFC3261; our scenario involves 1 SIP proxy. An audio
connection is established, connection is established,
2. Upon detection of Preamble by the terminating gateway, a SIP 2. Upon detection of Preamble by the terminating gateway, a SIP
re°INVITE request is sent to the emitting gateway to modify the re°INVITE request is sent to the emitting gateway to modify the
parameters of the session to add a T.38 fax connection. The parameters of the session to add a T.38 fax connection. The
connection data is specified per media description and not at the connection data is specified per media description and not at the
session-level. This allows the audio stream and t.38 fax stream to session-level. This allows the audio stream and t.38 fax stream to
be controlled independently (i.e., placing the audio on hold while be controlled independently (i.e., placing the audio on hold while
the t.38 fax transmission is active). Also note that the t.38 fax the t.38 fax transmission is active). Also note that the t.38 fax
media stream has been added to the session. This re-INVITE request media stream has been added to the session. This re-INVITE request
contains SDP information detailing the additional T.38 capabilities, contains SDP information detailing the additional T.38 capabilities,
3. It is suggested that the voice pipe be muted while the fax 3. It is suggested that the voice pipe be muted while the fax
session is in progress. Upon successful acknowledgments, T.38 IFP session is in progress. Upon successful acknowledgments, T.38 IFP
fax packets are sent/received on different UDP ports than the one fax packets are sent/received on different UDP ports than the one
used for audio RTP, used for audio RTP,
J-F. Mule/J. Li 25
SIP T.38 Call Flows February 2002
4. Once the fax transmission is terminated, audio capabilities are 4. Once the fax transmission is terminated, audio capabilities are
ŰrestoredŲ or the call is terminated. śśrestored∆∆ or the call is terminated.
5.3.1 Sequence Diagram 5.3.1 Sequence Diagram
IFT UA Proxy IFTGW UA IFT UA Proxy IFTGW UA
| | | | | |
| F1 INVITE | | | F1 INVITE | |
|------------------->| | |------------------->| |
| | F2 INVITE | | | F2 INVITE |
| |------------------->| | |------------------->|
| F3 100 Trying | | | F3 100 Trying | |
skipping to change at line 1365 skipping to change at line 1402
| F6 180 Ringing |<-------------------| | F6 180 Ringing |<-------------------|
|<-------------------| | |<-------------------| |
| | F7 200 OK | | | F7 200 OK |
| F8 200 OK |<-------------------| | F8 200 OK |<-------------------|
|<-------------------| | |<-------------------| |
| | | | | |
| F9 ACK | | | F9 ACK | |
|------------------->| F10 ACK | |------------------->| F10 ACK |
| ------------------->| | ------------------->|
| | | |
J-F. Mule/J. Li 27
SIP T.38 Call Flows February 2003
| Both Way RTP Media Established | | Both Way RTP Media Established |
Fax |<=======================================>| Fax |<=======================================>|
------->| | ------->| |
emitted | | | emitted | | |
| | | Preamble | | | Preamble
| | |<--------- | | |<---------
| | F11 INVITE | detected | | F11 INVITE | detected
| |<-------------------| | |<-------------------|
| F12 INVITE | | | F12 INVITE | |
|<-------------------| | |<-------------------| |
skipping to change at line 1390 skipping to change at line 1431
| | F15 ACK | | | F15 ACK |
| |<-------------------| | |<-------------------|
| F16 ACK | | | F16 ACK | |
|<-------------------| | |<-------------------| |
| | | |
| T.38/UDPT Fax Flow Established | | T.38/UDPT Fax Flow Established |
| Voice connection muted | | Voice connection muted |
|<=======================================>| |<=======================================>|
End of | | End of | |
fax | | | fax | | |
J-F. Mule/J. Li 26
SIP T.38 Call Flows February 2002
detected| | | detected| | |
------->| | | ------->| | |
| | | |
| | | End of fax | | | End of fax
| | |<---------- | | |<----------
| | | detected | | | detected
| | F17 INVITE | | | F17 INVITE |
| |<-------------------| | |<-------------------|
| F18 INVITE | | | F18 INVITE | |
|<-------------------| | |<-------------------| |
skipping to change at line 1421 skipping to change at line 1458
| |<-------------------| | |<-------------------|
| F22 ACK | | | F22 ACK | |
|<-------------------| | |<-------------------| |
| | | |
| Both way RTP Flow restored | | Both way RTP Flow restored |
|<=======================================>| |<=======================================>|
| | | |
| F23 BYE | | | F23 BYE | |
|------------------->| | |------------------->| |
| | F24 BYE | | | F24 BYE |
J-F. Mule/J. Li 28
SIP T.38 Call Flows February 2003
| |------------------->| | |------------------->|
| | | | | |
| | F25 200 OK | | | F25 200 OK |
| |<-------------------| | |<-------------------|
| F26 200 OK | | | F26 200 OK | |
|<-------------------| | |<-------------------| |
5.3.2 Message Details 5.3.2 Message Details
F1 INVITE IFT UA -> PROXY F1 INVITE IFT UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 70
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 146 Content-Length: 146
v=0 v=0
o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com
s=Session SDP s=Session SDP
J-F. Mule/J. Li 27
SIP T.38 Call Flows February 2002
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F2 INVITE PROXY -> IFTGW UA F2 INVITE PROXY -> IFTGW UA
INVITE sip:+1-650-555-2222@iftgw.there.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@iftgw.there.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 146 Content-Length: 146
v=0 v=0
o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com o=IFAXTERMINAL01 2890844527 2890844527 IN IP4 ift.here.com
s=Session SDP s=Session SDP
J-F. Mule/J. Li 29
SIP T.38 Call Flows February 2003
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F3 (100 Trying) PROXY -> IFT UA F3 (100 Trying) PROXY -> IFT UA
SIP/2.0 100 Trying SIP/2.0 100 Trying
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Content-Length: 0 Content-Length: 0
F4 100 Trying IFTGW UA -> PROXY F4 100 Trying IFTGW UA -> PROXY
SIP/2.0 100 Trying SIP/2.0 100 Trying
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 28
SIP T.38 Call Flows February 2002
F5 180 Ringing IFTGW UA -> PROXY F5 180 Ringing IFTGW UA -> PROXY
SIP/2.0 180 Ringing SIP/2.0 180 Ringing
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
F6 180 Ringing PROXY -> IFT UA F6 180 Ringing PROXY -> IFT UA
SIP/2.0 180 Ringing SIP/2.0 180 Ringing
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 30
SIP T.38 Call Flows February 2003
F7 200 OK IFTGW UA -> PROXY F7 200 OK IFTGW UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F8 200 OK PROXY -> IFT UA F8 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
J-F. Mule/J. Li 29
SIP T.38 Call Flows February 2002
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 INVITE CSeq: 17 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com o=IFAXTERMINAL01 2890844527 171089 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F9 ACK IFT UA -> PROXY F9 ACK IFT UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 70
J-F. Mule/J. Li 31
SIP T.38 Call Flows February 2003
Route: <sip:+1-650-555-2222@iftgw.there.com; Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 ACK CSeq: 17 ACK
Content-Length: 0 Content-Length: 0
F10 ACK PROXY -> IFTGW UA F10 ACK PROXY -> IFTGW UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@iftgw.there.com; Record-Route: <sip:+1-650-555-2222@iftgw.there.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 17 ACK CSeq: 17 ACK
Content-Length: 0 Content-Length: 0
/* RTP streams are established. The CNG fax tone is sent in-band if /* RTP streams are established. The CNG fax tone is sent in-band if
it is present. The receiving side IFT gateway DSP detects the it is present. The receiving side IFT gateway DSP detects the
Preamble. A new UDP port is open on IFTGW for T.38 IFP packets and Preamble. A new UDP port is open on IFTGW for T.38 IFP packets and
the IFTGW signals the switch over to fax mode by send a re-INVITE the IFTGW signals the switch over to fax mode by send a re-INVITE
with the new UDP port in the SDP */ with the new UDP port in the SDP */
J-F. Mule/J. Li 30
SIP T.38 Call Flows February 2002
F11 INVITE IFTGW UA -> PROXY F11 INVITE IFTGW UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 49172 udptl t38 m=image 49172 udptl t38
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
J-F. Mule/J. Li 32
SIP T.38 Call Flows February 2003
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F12 INVITE PROXY -> IFT UA F12 INVITE PROXY -> IFT UA
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
J-F. Mule/J. Li 31
SIP T.38 Call Flows February 2002
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 49172 udptl t38 m=image 49172 udptl t38
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F13 200 OK IFT UA -> PROXY F13 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
J-F. Mule/J. Li 33
SIP T.38 Call Flows February 2003
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 15002 udptl t38 m=image 15002 udptl t38
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F14 200 OK PROXY -> IFT UA F14 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
J-F. Mule/J. Li 32
SIP T.38 Call Flows February 2002
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 15002 udptl t38 m=image 15002 udptl t38
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F15 ACK IFTGW UA -> PROXY F15 ACK IFTGW UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com>
J-F. Mule/J. Li 34
SIP T.38 Call Flows February 2003
Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 ACK CSeq: 18 ACK
Content-Length: 0 Content-Length: 0
F16 ACK PROXY -> IFT UA F16 ACK PROXY -> IFT UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 ACK CSeq: 18 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 33
SIP T.38 Call Flows February 2002
/* T.38 fax transmission established both ways and the voice stream /* T.38 fax transmission established both ways and the voice stream
is muted */ is muted */
/* Then, the end of the fax transmission is detected on ingress side /* Then, the end of the fax transmission is detected on ingress side
and sent to the egress side (IFTGW). IFTGW initiates the switch back and sent to the egress side (IFTGW). IFTGW initiates the switch back
to voice communication */ to voice communication */
F17 INVITE IFTGW UA -> PROXY F17 INVITE IFTGW UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 181 Content-Length: 181
v=0 v=0
o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
J-F. Mule/J. Li 35
SIP T.38 Call Flows February 2003
F18 INVITE PROXY -> IFT UA F18 INVITE PROXY -> IFT UA
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 181 Content-Length: 181
v=0 v=0
o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
J-F. Mule/J. Li 34
SIP T.38 Call Flows February 2002
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F19 200 OK IFT UA -> PROXY F19 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F20 200 OK PROXY -> IFTGW UA F20 200 OK PROXY -> IFTGW UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com;
maddr=obelix.wcom.com> J-F. Mule/J. Li 36
SIP T.38 Call Flows February 2003
Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com o=faxgw1 2890844527 2890844529 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
F21 ACK IFTGW UA -> PROXY F21 ACK IFTGW UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
J-F. Mule/J. Li 35
SIP T.38 Call Flows February 2002
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 ACK CSeq: 19 ACK
Content-Length: 0 Content-Length: 0
F22 ACK PROXY -> IFT UA F22 ACK PROXY -> IFT UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 ACK CSeq: 19 ACK
Content-Length: 0 Content-Length: 0
F23 BYE IFT UA -> PROXY F23 BYE IFT UA -> PROXY
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
J-F. Mule/J. Li 37
SIP T.38 Call Flows February 2003
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Length: 0 Content-Length: 0
F24 BYE PROXY -> IFTGW UA F24 BYE PROXY -> IFTGW UA
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Length: 0 Content-Length: 0
F25 200 OK IFTGW UA -> PROXY F25 200 OK IFTGW UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde24
J-F. Mule/J. Li 36
SIP T.38 Call Flows February 2002
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde24
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
F26 200 OK PROXY -> IFT UA F26 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde24 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde24
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
5.4 SIP T.38 fax call Ż fax stream forced to replace voice stream 5.4 SIP T.38 fax call - - fax stream forced to replace voice stream
This section illustrates the following scenario: This section illustrates the following scenario:
J-F. Mule/J. Li 38
SIP T.38 Call Flows February 2003
1. A SIP INVITE is sent to the called party requesting a voice 1. A SIP INVITE is sent to the called party requesting a voice
connection per RFC2543; our scenario involves 1 SIP proxy. An audio connection per RFC3261; our scenario involves 1 SIP proxy. An audio
connection is established, connection is established,
2. Upon detection of Preamble by the terminating gateway, a SIP 2. Upon detection of Preamble by the terminating gateway, a SIP
re°INVITE request is sent to the emitting gateway to modify the re°INVITE request is sent to the emitting gateway to modify the
parameters of the session to add a T.38 fax connection. This re- parameters of the session to add a T.38 fax connection. This re-
INVITE request contains SDP information detailing the additional INVITE request contains SDP information detailing the additional
T.38 capabilities. It is also suggested that the voice pipe be T.38 capabilities. It is also suggested that the voice pipe be
muted while the fax session is in progress. muted while the fax session is in progress.
3. The emitting gateway does not have the resources to maintain both 3. The emitting gateway does not have the resources to maintain both
the audio & fax streams and replies by allowing the fax media the audio & fax streams and replies by allowing the fax media
stream. Upon successful acknowledgments, the audio stream is stream. Upon successful acknowledgments, the audio stream is
terminated and T.38 IFP fax packets are exchanged, terminated and T.38 IFP fax packets are exchanged,
4. Once the fax transmission is terminated, audio capabilities are 4. Once the fax transmission is terminated, audio capabilities are
Űre-negotiatedŲ and the call is terminated. śśre-negotiated∆∆ and the call is terminated.
5.4.1 Sequence Diagram 5.4.1 Sequence Diagram
Refer to section 5.3.1; sequence diagram is unchanged. Refer to section 5.3.1; sequence diagram is unchanged.
5.4.2 Message Details 5.4.2 Message Details
See section 5.3.2 for the complete set of messages. We only See section 5.3.2 for the complete set of messages. We only
indicate the changed messages based on the emitting gateway∆s indicate the changed messages based on the emitting gateway∆s
decline to support both voice and fax streams. decline to support both voice and fax streams.
... ...
F11 INVITE IFTGW UA -> PROXY F11 INVITE IFTGW UA -> PROXY
J-F. Mule/J. Li 37 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
SIP T.38 Call Flows February 2002 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Max-Forwards: 70
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 Route: <sip:+1-650-555-2222@obelix.banyuls.com;
Via: SIP/2.0/UDP iftgw.there.com:5060 maddr=obelix.banyuls.com>
Route: <sip:+1-650-555-2222@obelix.wcom.com;
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 49172 udptl t38 m=image 49172 udptl t38
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0 J-F. Mule/J. Li 39
a=T38FaxTranscodingJBIG:0 SIP T.38 Call Flows February 2003
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F12 INVITE PROXY -> IFT UA F12 INVITE PROXY -> IFT UA
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com o=faxgw1 2890844527 171090 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
J-F. Mule/J. Li 38
SIP T.38 Call Flows February 2002
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 49172 udptl t38 m=image 49172 udptl t38
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPFEC a=T38FaxUdpEC:t38UDPFEC
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F13 200 OK IFT UA -> PROXY F13 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060;
Via: SIP/2.0/UDP iftgw.there.com:5060 branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-
2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
J-F. Mule/J. Li 40
SIP T.38 Call Flows February 2003
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 0 RTP/AVP 0 m=audio 0 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 15002 udptl t38 m=image 15002 udptl t38
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F14 200 OK PROXY -> IFT UA F14 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
J-F. Mule/J. Li 39
SIP T.38 Call Flows February 2002
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-
2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 320 Content-Length: 320
v=0 v=0
o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com o=faxgw1 2890846527 2890846528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
t=0 0 t=0 0
m=audio 0 RTP/AVP 0 m=audio 0 RTP/AVP 0
c=IN IP4 0.0.0.0 c=IN IP4 0.0.0.0
m=image 15002 udptl t38 m=image 15002 udptl t38
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
a=T38FaxVersion:0 a=T38FaxVersion:0
a=T38MaxBitRate:14400 a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:72 a=T38FaxMaxBuffer:72
a=T38FaxMaxDatagram:316 a=T38FaxMaxDatagram:316
a=T38FaxUdpEC:t38UDPRedundancy a=T38FaxUdpEC:t38UDPRedundancy
F15 ACK IFTGW UA -> PROXY F15 ACK IFTGW UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060
Route: <sip:+1-650-555-2222@obelix.wcom.com; J-F. Mule/J. Li 41
maddr=obelix.wcom.com> SIP T.38 Call Flows February 2003
Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Max-Forwards: 70
Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-
2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 ACK CSeq: 18 ACK
Content-Length: 0 Content-Length: 0
F16 ACK PROXY -> IFT UA F16 ACK PROXY -> IFT UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060;
Via: SIP/2.0/UDP iftgw.there.com:5060 branch=z9hG4bK2d008.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
maddr=obelix.wcom.com> Max-Forwards: 69
Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-
2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 ACK CSeq: 18 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 40
SIP T.38 Call Flows February 2002
6. Unsuccessful Scenarios 6. Unsuccessful Scenarios
6.1. Unsuccessful T.38 fax scenario Ż no support for T.38 6.1. Unsuccessful T.38 fax scenario - - no support for T.38
This section represents a SIP T.38 call failure because the emitting This section represents a SIP T.38 call failure because the emitting
gateway does not support T.38. gateway does not support T.38.
Scenario: Scenario:
1. A SIP INVITE is sent to the called party requesting a voice 1. A SIP INVITE is sent to the called party requesting a voice
connection per RFC2543; our scenario involves 1 SIP proxy. An audio connection per RFC3261; our scenario involves 1 SIP proxy. An audio
connection is established, connection is established,
2. Upon detection of Preamble by the terminating gateway, a SIP 2. Upon detection of Preamble by the terminating gateway, a SIP
re°INVITE request is sent to the emitting gateway to modify the re°INVITE request is sent to the emitting gateway to modify the
parameters of the session to allow a T.38 fax connection. This re- parameters of the session to allow a T.38 fax connection. This re-
INVITE request contains SDP information detailing T.38 capabilities, INVITE request contains SDP information detailing T.38 capabilities,
3. The emitting gateway rejects the re°INVITE with a 415 Unsupported 3. The emitting gateway rejects the re°INVITE with a 415 Unsupported
Media Type response. Media Type response.
4. Upon reception of the reject, the call is terminated. 4. Upon reception of the reject, the call is terminated.
6.1.1. Sequence Diagram 6.1.1. Sequence Diagram
The messages F1 to F12 are identical to section 5.2. The messages F1 to F12 are identical to section 5.2.
J-F. Mule/J. Li 42
SIP T.38 Call Flows February 2003
IFT UA Proxy IFTGW UA IFT UA Proxy IFTGW UA
| | | | | |
| F1 INVITE | | | F1 INVITE | |
|------------------->| | |------------------->| |
| | F2 INVITE | | | F2 INVITE |
| |------------------->| | |------------------->|
| F3 100 Trying | | | F3 100 Trying | |
|<-------------------| F4 100 Trying | |<-------------------| F4 100 Trying |
| |<-------------------| | |<-------------------|
| | | | | |
skipping to change at line 2199 skipping to change at line 2242
|------------------->| F10 ACK | |------------------->| F10 ACK |
| ------------------->| | ------------------->|
| | | |
| Both Way RTP Media Established | | Both Way RTP Media Established |
Fax |<=======================================>| Fax |<=======================================>|
------->| | ------->| |
emitted | | | emitted | | |
| | | Preamble | | | Preamble
| | |<--------- | | |<---------
| | F11 INVITE | detected | | F11 INVITE | detected
J-F. Mule/J. Li 41
SIP T.38 Call Flows February 2002
| |<-------------------| | |<-------------------|
| F12 INVITE | | | F12 INVITE | |
|<-------------------| | |<-------------------| |
| | | | | |
| F13 415 | | | F13 415 | |
|------------------->| | |------------------->| |
| | F14 415 | | | F14 415 |
| |------------------->| | |------------------->|
| | | | | |
| | F15 BYE | | | F15 BYE |
skipping to change at line 2228 skipping to change at line 2267
|------------------->| | |------------------->| |
| | F18 200 OK | | | F18 200 OK |
| |------------------->| | |------------------->|
6.1.2. Message Details 6.1.2. Message Details
Messages F1 to F12 are identical to section 5.2; refer to 5.2. Messages F1 to F12 are identical to section 5.2; refer to 5.2.
F13 415 Unsupported Media Type IFT UA -> PROXY F13 415 Unsupported Media Type IFT UA -> PROXY
J-F. Mule/J. Li 43
SIP T.38 Call Flows February 2003
SIP/2.0 415 Unsupported Media Type SIP/2.0 415 Unsupported Media Type
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Length: 0 Content-Length: 0
F14 415 Unsupported Media Type PROXY -> IFTGW UA F14 415 Unsupported Media Type PROXY -> IFTGW UA
SIP/2.0 415 Unsupported Media Type SIP/2.0 415 Unsupported Media Type
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d010.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=2d010.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Length: 0 Content-Length: 0
F15 BYE IFTGW UA -> PROXY F15 BYE IFTGW UA -> PROXY
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
J-F. Mule/J. Li 42 Max-Forwards: 70
SIP T.38 Call Flows February 2002 Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
Via: SIP/2.0/UDP iftgw.there.com:5060
Route: <sip:+1-650-555-2222@obelix.wcom.com;
maddr=obelix.wcom.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 BYE CSeq: 19 BYE
Content-Length: 0 Content-Length: 0
F16 BYE PROXY -> IFT UA F16 BYE PROXY -> IFT UA
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d010.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=2d010.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 BYE CSeq: 19 BYE
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 44
SIP T.38 Call Flows February 2003
F17 200 OK IFT UA -> PROXY F17 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 BYE CSeq: 19 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
F18 200 OK PROXY -> IFTGW UA F18 200 OK PROXY -> IFTGW UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060 Via: SIP/2.0/UDP obelix.banyuls.com:5060
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 BYE CSeq: 19 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
6.2. Unsuccessful T.38 fax scenario Ż 488/606 response & G.711 fallback 6.2. Unsuccessful T.38 fax scenario - - 488/606 rsp & G.711 fallback
J-F. Mule/J. Li 43
SIP T.38 Call Flows February 2002
This section represents an unsuccessful SIP T.38 fax call: when the This section represents an unsuccessful SIP T.38 fax call: when the
emitting gateway does not support T.38 fax relay, it SHOULD respond emitting gateway does not support T.38 fax relay, it SHOULD respond
with either a Ű488 Not Acceptable HereŲ response or a Ű606 Not with either a śś488 Not Acceptable Here∆∆ response or a śś606 Not
AcceptableŲ response to indicate that some aspects of the session Acceptable∆∆ response to indicate that some aspects of the session
description are not acceptable. The terminating gateway SHOULD description are not acceptable. The terminating gateway SHOULD
react by proposing a fallback to G.711 fax pass-through with special react by proposing a fallback to G.711 fax pass-through with special
codec characteristics Ż echo cancellation ON, silence suppression codec characteristics - -silence suppression OFF. The message details
OFF. The message details in this section make use of the generic in this section make use of the generic SDP attribute silenceSupp
SDP attributes ecan and silenceSupp, defined in RFC3108 [10]. defined in RFC3108 [10].
Scenario: Scenario:
1. A SIP INVITE is sent to the called party requesting a voice 1. A SIP INVITE is sent to the called party requesting a voice
connection per RFC2543; our scenario involves 1 SIP proxy. An audio connection per RFC3261; our scenario involves 1 SIP proxy. An audio
connection is established, connection is established,
2. Upon detection of Preamble by the terminating gateway, a SIP 2. Upon detection of Preamble by the terminating gateway, a SIP
re°INVITE request is sent to the emitting gateway to modify the re°INVITE request is sent to the emitting gateway to modify the
parameters of the session to allow a T.38 fax connection. This re- parameters of the session to allow a T.38 fax connection. This re-
INVITE request contains SDP information detailing T.38 capabilities, INVITE request contains SDP information detailing T.38 capabilities,
3. The emitting gateway rejects the re-INVITE with a 488 or 606 3. The emitting gateway rejects the re-INVITE with a 488 or 606
response. Upon reception of the reject, the terminating gateway response. Upon reception of the reject, the terminating gateway
proposes to use plain G.711 to carry the fax stream. proposes to use plain G.711 to carry the fax stream.
4. The call is terminated. 4. The call is terminated.
J-F. Mule/J. Li 45
SIP T.38 Call Flows February 2003
6.2.1. Sequence Diagram 6.2.1. Sequence Diagram
The messages F1 to F12 are identical to section 5.2. The messages F1 to F12 are identical to section 5.2.
IFT UA Proxy IFTGW UA IFT UA Proxy IFTGW UA
| | | | | |
| F1 INVITE | | | F1 INVITE | |
|------------------->| | |------------------->| |
| | F2 INVITE | | | F2 INVITE |
| |------------------->| | |------------------->|
| F3 100 Trying | | | F3 100 Trying | |
skipping to change at line 2360 skipping to change at line 2403
| F9 ACK | | | F9 ACK | |
|------------------->| F10 ACK | |------------------->| F10 ACK |
| ------------------->| | ------------------->|
| | | |
| Both Way RTP Media Established | | Both Way RTP Media Established |
Fax |<=======================================>| Fax |<=======================================>|
------->| | ------->| |
emitted | | | emitted | | |
| | | Preamble | | | Preamble
| | |<--------- | | |<---------
J-F. Mule/J. Li 44
SIP T.38 Call Flows February 2002
| | F11 INVITE | detected | | F11 INVITE | detected
| |<-------------------| | |<-------------------|
| F12 INVITE | | | F12 INVITE | |
|<-------------------| | |<-------------------| |
| | | | | |
| F13 606 | | | F13 606 | |
|------------------->| | |------------------->| |
| | F14 606 (or 488) | | | F14 606 (or 488) |
| |------------------->| | |------------------->|
| | F15 INVITE | | | F15 INVITE |
skipping to change at line 2387 skipping to change at line 2426
| F17 200 OK | | | F17 200 OK | |
|------------------->| | |------------------->| |
| | F18 200 OK | | | F18 200 OK |
| |------------------->| | |------------------->|
| | | | | |
| | F19 ACK | | | F19 ACK |
| |<-------------------| | |<-------------------|
| F20 ACK | | | F20 ACK | |
|<-------------------| | |<-------------------| |
| | | |
J-F. Mule/J. Li 46
SIP T.38 Call Flows February 2003
| G.711 RTP Flow Established | | G.711 RTP Flow Established |
|<=======================================>| |<=======================================>|
| for fax pass-through | | for fax pass-through |
| | | |
| F21 BYE | | | F21 BYE | |
|------------------->| | |------------------->| |
| | F22 BYE | | | F22 BYE |
| |------------------->| | |------------------->|
| | | | | |
| | F23 200 OK | | | F23 200 OK |
skipping to change at line 2412 skipping to change at line 2455
Messages F1 to F12 are identical to section 5.2; refer to 5.2. Messages F1 to F12 are identical to section 5.2; refer to 5.2.
F13 606 Not Acceptable IFT UA -> PROXY F13 606 Not Acceptable IFT UA -> PROXY
SIP/2.0 606 Not Acceptable SIP/2.0 606 Not Acceptable
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Warning: 304 Media type not available: One or more media types Warning: 304 Media type not available: One or more media types
contained in the session description are not available. contained in the session description are not available.
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
J-F. Mule/J. Li 45
SIP T.38 Call Flows February 2002
Content-Length: 0 Content-Length: 0
F14 606 Not Acceptable PROXY -> IFTGW UA F14 606 Not Acceptable PROXY -> IFTGW UA
SIP/2.0 606 Not Acceptable SIP/2.0 606 Not Acceptable
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d010.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=2d010.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Warning: 304 Media type not available: One or more media types Warning: 304 Media type not available: One or more media types
contained in the session description are not available. contained in the session description are not available.
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 18 INVITE CSeq: 18 INVITE
Content-Length: 0 Content-Length: 0
F15 INVITE IFTGW UA -> PROXY F15 INVITE IFTGW UA -> PROXY
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
J-F. Mule/J. Li 47
SIP T.38 Call Flows February 2003
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 181 Content-Length: 181
v=0 v=0
o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
a=ecan:fb on -
a=silenceSupp:off - - - - a=silenceSupp:off - - - -
F16 INVITE PROXY -> IFT UA F16 INVITE PROXY -> IFT UA
INVITE sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 INVITE sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
J-F. Mule/J. Li 46
SIP T.38 Call Flows February 2002
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-650-555-2222@iftgw.there.com> Contact: <sip:+1-650-555-2222@iftgw.there.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 181 Content-Length: 181
v=0 v=0
o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com o=faxgw1 2890844527 171091 IN IP4 iftgw.there.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.there.com c=IN IP4 iftmg.there.com
t=0 0 t=0 0
m=audio 12322 RTP/AVP 0 m=audio 12322 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
a=ecan:fb on -
a=silenceSupp:off - - - - a=silenceSupp:off - - - -
F17 200 OK IFT UA -> PROXY F17 200 OK IFT UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d008.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d008.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17
J-F. Mule/J. Li 48
SIP T.38 Call Flows February 2003
To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 150 Content-Length: 150
v=0 v=0
o=faxgw1 2890844527 2890844528 IN IP4 ift.here.com o=faxgw1 2890844527 2890844528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
a=ecan:fb on -
a=silenceSupp:off - - - - a=silenceSupp:off - - - -
F18 200 OK PROXY -> IFTGW UA F18 200 OK PROXY -> IFTGW UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 INVITE CSeq: 19 INVITE
Contact: <sip:+1-303-555-1111@ift.here.com> Contact: <sip:+1-303-555-1111@ift.here.com>
Content-Type: application/sdp Content-Type: application/sdp
J-F. Mule/J. Li 47
SIP T.38 Call Flows February 2002
Content-Length: 150 Content-Length: 150
v=0 v=0
o=faxgw1 2890844527 2890844528 IN IP4 ift.here.com o=faxgw1 2890844527 2890844528 IN IP4 ift.here.com
s=Session SDP s=Session SDP
c=IN IP4 iftmg.here.com c=IN IP4 iftmg.here.com
t=0 0 t=0 0
m=audio 3456 RTP/AVP 0 m=audio 3456 RTP/AVP 0
a=rtpmap:0 PCMU/8000 a=rtpmap:0 PCMU/8000
a=ecan:fb on -
a=silenceSupp:off - - - - a=silenceSupp:off - - - -
F19 ACK IFTGW UA -> PROXY F19 ACK IFTGW UA -> PROXY
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 ACK CSeq: 19 ACK
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 49
SIP T.38 Call Flows February 2003
F20 ACK PROXY -> IFT UA F20 ACK PROXY -> IFT UA
ACK sip:+1-650-555-2222@obelix.wcom.com;user=phone SIP/2.0 ACK sip:+1-650-555-2222@obelix.banyuls.com;user=phone SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP iftgw.there.com:5060 Via: SIP/2.0/UDP iftgw.there.com:5060;branch=z9hG4bK2d017.1
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab11
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde17 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde17
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 19 ACK CSeq: 19 ACK
Content-Length: 0 Content-Length: 0
/* G.711 audio streams established both ways for fax pass through */ /* G.711 audio streams established both ways for fax pass through */
F21 BYE IFT UA -> PROXY F21 BYE IFT UA -> PROXY
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 70
maddr=obelix.wcom.com> Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
J-F. Mule/J. Li 48
SIP T.38 Call Flows February 2002
Content-Length: 0 Content-Length: 0
F22 BYE PROXY -> IFTGW UA F22 BYE PROXY -> IFTGW UA
BYE sip:+1-650-555-2222@obelix.wcom.com SIP/2.0 BYE sip:+1-650-555-2222@obelix.banyuls.com SIP/2.0
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d009.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d009.1
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Max-Forwards: 69
maddr=obelix.wcom.com> Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Length: 0 Content-Length: 0
F23 200 OK IFTGW UA -> PROXY F23 200 OK IFTGW UA -> PROXY
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP obelix.wcom.com:5060; branch=2d007.1 Via: SIP/2.0/UDP obelix.banyuls.com:5060; branch=z9hG4bK2d007.1
J-F. Mule/J. Li 50
SIP T.38 Call Flows February 2003
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
F24 200 OK PROXY -> IFT UA F24 200 OK PROXY -> IFT UA
SIP/2.0 200 OK SIP/2.0 200 OK
Via: SIP/2.0/UDP ift.here.com:5060 Via: SIP/2.0/UDP ift.here.com:5060
Record-Route: <sip:+1-650-555-2222@obelix.wcom.com; Record-Route: <sip:+1-650-555-2222@obelix.banyuls.com;
maddr=obelix.wcom.com> maddr=obelix.banyuls.com>
From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22 From: sip:+1-303-555-1111@ift.here.com;user=phone;tag=ab22
To: sip:+1-650-555-2222@obelix.wcom.com;user=phone;tag=cde34 To: sip:+1-650-555-2222@obelix.banyuls.com;user=phone;tag=cde34
Call-ID: 1717@ift.here.com Call-ID: 1717@ift.here.com
CSeq: 20 BYE CSeq: 20 BYE
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: 0 Content-Length: 0
J-F. Mule/J. Li 49 J-F. Mule/J. Li 51
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
7. SDP Attribute Table for T.38 sessions 7. SDP Attribute Table for T.38 sessions
For a detailed description of these attributes, refer to IANA. The For a detailed description of these attributes, refer to IANA∆s SDP
tables below are replicated here for reference only. parameters registration page. The tables below are replicated here
for information only.
+-----------------------+---------------------+--------------+ +-----------------------+---------------------+---------------+
| SDP Attribute Name | Appropriate values | Example | | SDP Attribute Name | Appropriate values | Example |
| ("att-field") | | | | ("att-field") | | |
+-----------------------+---------------------+--------------+ +-----------------------+---------------------+---------------+
| | | | | | | |
| T38FaxVersion | 1*DIGIT | 0 | | T38FaxVersion | 1*DIGIT | 0 |
| | | | | | | |
| T38MaxBitRate | 1*(DIGIT) | 14400 | | T38MaxBitRate | 1*(DIGIT) | 14400 |
| | | | | | | |
| T38FaxFillBitRemoval | boolean | 0 | | T38FaxFillBitRemoval | boolean |true if present|
| | | | | | | |
| T38FaxTranscodingMMR | boolean | 0 | | T38FaxTranscodingMMR | boolean |true if present|
| | | | | | | |
| T38FaxTranscodingJBIG | boolean | 0 | | T38FaxTranscodingJBIG | boolean |true if present|
| | | | | | | |
| T38FaxRateManagement | localTCF | |transferredTCF| | T38FaxRateManagement | localTCF | |transferredTCF|
| | transferredTCF | | | | transferredTCF | |
| | | | | | | |
| T38FaxMaxBuffer | 1*(DIGIT); optional | 72 | | T38FaxMaxBuffer | 1*(DIGIT); optional | 72 |
| | | (bytes) | | | | (bytes) |
| | | | | | | |
| T38FaxMaxDatagram | 1*(DIGIT); | Depends on | | T38FaxMaxDatagram | 1*(DIGIT); | Depends on |
| | optional | redundancy; | | | optional | redundancy; |
| | | 316 (bytes)| | | | 316 (bytes)|
| | | | | | | |
| T38FaxUdpEC | t38UDPFEC | | T38UDPRedund | | T38FaxUdpEC | t38UDPFEC | | T38UDPRedund |
| | t38UDPRedundancy | ancy | | | t38UDPRedundancy | ancy |
+-----------------------+---------------------+--------------+ +-----------------------+---------------------+---------------+
Registered SDP Protocol ŰprotoŲ for T.38: Registered SDP Protocol śśproto∆∆ for T.38:
+-----------------+ +-----------------+
| Name | | Name |
| | | |
+-----------------+ +-----------------+
| | | |
| UDPTL | | UDPTL |
| | | |
| TCP | | TCP |
| | | |
+-----------------+ +-----------------+
Registered SDP Protocol ŰfmtŲ, MIME media type image/t38: Registered SDP Protocol śśfmt∆∆, MIME media type image/t38:
Registered Real-time Facsimile (T.38) - image/t38 MIME Sub-type is
defined in [11];
MIME media type name: image MIME media type name: image
MIME subtype name: t38 MIME subtype name: t38
J-F. Mule/J. Li 50 J-F. Mule/J. Li 52
SIP T.38 Call Flows February 2002 SIP T.38 Call Flows February 2003
8. Considerations 8. Considerations
In this temporary section, we log the open items for discussion as In this temporary section, we log the open items for discussion as
well as issues that have been solved on the mailing list: well as issues that have been solved on the mailing list:
8.1. Level of requirements for Internet gateways 8.1. Level of requirements for Internet gateways
--- Status: closed, solved by old draft01 text in section 4.2 --- Status: closed, solved by old draft01 text in section 4.2
Based on the comments received on old draft-00, the authors Based on the comments received on old draft-00, the authors
recommend that: T.38 Internet fax gateways MUST trigger a SIP re- recommend that: T.38 Internet fax gateways MUST trigger a SIP re-
skipping to change at line 2698 skipping to change at line 2745
8.2. Negotiation of UDP ports for T.38 transmission 8.2. Negotiation of UDP ports for T.38 transmission
--- Status: not an issue, just logged here --- Status: not an issue, just logged here
When switching to T.38 mode, Internet fax gateways specify a new set When switching to T.38 mode, Internet fax gateways specify a new set
of parameters for the media connection in SDP. Some gateways may of parameters for the media connection in SDP. Some gateways may
choose the UDP/RTP port used in audio mode for UDP/UDPTL/T.38 choose the UDP/RTP port used in audio mode for UDP/UDPTL/T.38
traffic. Some gateways may choose to open a new UDP port for traffic. Some gateways may choose to open a new UDP port for
UDPTL/T.38 fax (and keep the previous UDP/RTP port open for the UDPTL/T.38 fax (and keep the previous UDP/RTP port open for the
switch back to audio). switch back to audio).
SDP provides the mechanism to precisely define in SIP all cases: SDP provides the mechanism to precisely define in SIP all cases:
- if an Internet Fax gateway desires to re-use the UDP/RTP port for - if an Internet Fax gateway desires to re-use the UDP/RTP port for
UDP/UDPTL/T.38, put 1 Űm=Ų line in the re-INVITE. UDP/UDPTL/T.38, put 1 śśm=∆∆ line in the re-INVITE.
m=image <original_RTP_port> udptl t38 m=image <original_RTP_port> udptl t38
- if an Internet Fax gateway desires to release the RTP port and - if an Internet Fax gateway desires to release the RTP port and
open a new UDP port for T.38: open a new UDP port for T.38:
m=image <new_UDP_port> udptl t38 m=image <new_UDP_port> udptl t38
- if an Internet Fax gateway desires to keep the RTP port for future - if an Internet Fax gateway desires to keep the RTP port for future
use in the session and open a new UDP port for T.38, we need to use in the session and open a new UDP port for T.38, we need to
repeat the RTP/AVP port: repeat the RTP/AVP port:
m=audio <original_RTP_port> RTP/AVP 0 m=audio <original_RTP_port> RTP/AVP 0
m=image <new_UDP_port> udptl t38 m=image <new_UDP_port> udptl t38
skipping to change at line 2725 skipping to change at line 2772
8.4. Adding text to make use of SIP OPTIONS: in progress in draft-02 8.4. Adding text to make use of SIP OPTIONS: in progress in draft-02
--- Status: Open for discussion --- Status: Open for discussion
As discussed with Bill Sulzen, the SIP OPTIONS response could be As discussed with Bill Sulzen, the SIP OPTIONS response could be
used to assert that real-time fax communications using either T.38 used to assert that real-time fax communications using either T.38
or fax-passthrough are supported. This could certainly improve the or fax-passthrough are supported. This could certainly improve the
negotiation phases and reduce the number of SIP messages. It is negotiation phases and reduce the number of SIP messages. It is
also key to get the capabilities of the Internet-aware fax device or also key to get the capabilities of the Internet-aware fax device or
gateway other than on a per call basis. gateway other than on a per call basis.
What needs to be added: What needs to be added:
J-F. Mule/J. Li 53
SIP T.38 Call Flows February 2003
- add text in sub-section in section 4.5 - add text in sub-section in section 4.5
- specify how the Accept header line should be populated (do we - specify how the Accept header line should be populated (do we
want to specify t.38 and/or fax pass-through (meaning ability to want to specify t.38 and/or fax pass-through (meaning ability to
support silencesuppression), and within t.38, do we want to specify
J-F. Mule/J. Li 51 whether it is t.38 over tcp, udptl, both, etc.
SIP T.38 Call Flows February 2002
support ecan and silencesuppression), and within t.38, do we want to
specify whether it is t.38 over tcp, udptl, both, etc.
8.5. Use of IP addresses in SDP connection information 8.5. Use of IP addresses in SDP connection information
--- Status: Open for discussion --- Status: Closed, remains unchanged per sipping call flow ID
Comment from Christer Holmberg: SDP connection information should Comment from Christer Holmberg: SDP connection information should
use IP addresses instead of domain names (as per draft-ietf-mmusic- use IP addresses instead of domain names (as per draft-ietf-mmusic-
sdp-new-03) sdp-new-03)
8.6. Unsuccessful scenario: 606 or 488 8.6. Unsuccessful scenario: 606 or 488
--- Status: closed --- Status: Closed
Comment from Bill Sulzen: it is acceptable or even preferable to Comment from Bill Sulzen: it is acceptable or even preferable to
reject with a 488 Not Acceptable Media? reject with a 488 Not Acceptable Media?
Resolution: treat 606 and 488 as equally appropriate. Resolution: treat 606 and 488 as equally appropriate.
8.7. SIP re-INVITE or UPDATE?
--- Status: open with the following recommendation
In most cases, the SIP dialog is established when the codec changes
occur so the use of UPDATE is not required. Also the re-INVITE is
more standard so we propose to use re-INVITE.
9. Security Considerations 9. Security Considerations
The security mechanisms provided in RFC2543 apply: message This document contains examples of SIP session establishment of
authentication can be performed on SIP INVITEs and also BYE. particular media types. The security considerations in RFC 3261 [3]
apply. There is no known additional security threats because of the
nature of the media descriptors exchanged in these call flows.
RFC 3261 describes the basic threats including server impersonation,
message body tampering, session modifying or teardown, and denial of
service and amplification attacks.
The use of TLS and the Secure SIP (sips) URI scheme provides a
better level of security including two-way authentication. IPsec can
also improve security.
S/MIME can provide end-to-end confidentiality and integrity
protection of message bodies, as described in RFC 3261.
10. References 10. References
1 S. Bradner, "The Internet Standards Process -- Revision 3", BCP 1 S. Bradner, "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996. 9, RFC 2026, October 1996.
2 S. Bradner, "Key words for use in RFCs to Indicate Requirement 2 S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
3 M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg, "SIP: 3 Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Session Initiation Protocol", RFC 2543, March 1999. Peterson, J., Sparks, R., Handley, M., and Schooler, E., "SIP:
4 ITU-T Recommendation T.38, ŰProcedures for real-time Group 3 J-F. Mule/J. Li 54
facsimile communication over IP networksŲ, June 1998. SIP T.38 Call Flows February 2003
5 Johnston, et al, ŰSIP Telephony Call Flow ExamplesŲ, Internet- Session Initiation Protocol", RFC 3261, June 2002.
Draft draft-ietf-sip-call-flows-05.txt, June 2001.
6 ITU-T Recommendation T.38 Amendment 2, ŰProcedures for real-time 4 ITU-T Recommendation T.38, śśProcedures for real-time Group 3
Group 3 facsimile communication over IP networksŲ, February 2000. facsimile communication over IP networks∆∆, June 1998.
7 ITU-T Recommendation T.30, ŰProcedures for document facsimile 5 Johnston, et al, śśSIP Basic Call Flow Examples∆∆, Internet-Draft
transmission in the general switched telephone networkŲ, March draft-ietf-sipping-basic-call-flows-01.txt, October 2002.
6 ITU-T Recommendation T.38, śśProcedures for real-time Group 3
facsimile communication over IP networks∆∆, March 2002.
7 ITU-T Recommendation T.30, śśProcedures for document facsimile
transmission in the general switched telephone network∆∆, March
1993. 1993.
8 M. Handley, V. Jacobson, "SDP: session description protocol", 8 M. Handley, V. Jacobson, "SDP: session description protocol",
RFC 2327, April 1998. RFC 2327, April 1998.
9 ITU-T Recommendation T.38 Amendment 2 Annex D, ŰSIP/SDP Call 9 ITU-T Recommendation T.38 Amendment 2 Annex D, śśSIP/SDP Call
Establishment ProceduresŲ, February 2000. Establishment Procedures∆∆, February 2000.
J-F. Mule/J. Li 52
SIP T.38 Call Flows February 2002
10 R. Kumar, M. Mostafa, ŰConventions for the use of the Session 10 R. Kumar, M. Mostafa, śśConventions for the use of the Session
Description Protocol (SDP) for ATM Bearer ConnectionsŲ, RFC3108, Description Protocol (SDP) for ATM Bearer Connections∆∆, RFC3108,
May 2001. May 2001.
11. Acknowledgments 11 G. Parsons, śśReal-time Facsimile (T.38) - image/t38 MIME Sub-type
Registration∆∆, RFC3362, August 2002.
1. Acknowledgments
This document would not have been possible without the help of the This document would not have been possible without the help of the
following development engineers and fax experts, in particular following development engineers and fax experts, in particular
Stanley Khouw, Bill Michalek, and George Maphis of Clarent Stanley Khouw, Bill Michalek, and George Maphis of Clarent
Corporation. Corporation.
The authors would like to thank Bill Sulzen of Cisco Systems for his The authors would like to thank Bill Sulzen of Cisco Systems for his
continued support and critical comments. We also acknowledge the continued support and critical comments. We also acknowledge the
valuable contributions from Flemming Andreasen of Cisco Systems, valuable contributions from Flemming Andreasen of Cisco Systems,
Christer Holmberg of Ericsson, and Bert Culpepper of InterVoice- Christer Holmberg of Ericsson, and Bert Culpepper of InterVoice-
Brite. Brite.
Many thanks to the reviewers of the previous document for their Many thanks to the reviewers of the previous document for their
comments: Jim Renkel of 3COM, Sudipto Mukherjee of Cisco Systems, comments: Jim Renkel of 3COM, Sudipto Mukherjee of Cisco Systems,
Arjun Roychowdhury of Hughes Software Systems. Arjun Roychowdhury of Hughes Software Systems.
12. Author's Addresses 2. Author's Addresses
Jieying Li Jieying Li
iVox Networks
26701 West Agoura Road
Calabasa, CA 91302
email:jieying.li@ivoxnetworks.com email:jieying.li@ivoxnetworks.com
Jean-Francois Mule∆ Jean-Francois Mule∆
CableLabs CableLabs
J-F. Mule/J. Li 55
SIP T.38 Call Flows February 2003
400 Centennial Parkway 400 Centennial Parkway
Louisville, CO 80027 Louisville, CO 80027
USA USA
email: jf.mule@cablelabs.com email: jfm@cablelabs.com
Full Copyright Statement ull Copyright Statement
"Copyright (C) The Internet Society 2003. All Rights Reserved.
"Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into followed, or as required to translate it into languages other than
English.
J-F. Mule/J. Li 53 The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
cknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
-F. Mule/J. Li 56
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/