draft-ietf-mmusic-sdp-cs-15.txt   draft-ietf-mmusic-sdp-cs-16.txt 
MMUSIC WG M. Garcia-Martin MMUSIC WG M. Garcia-Martin
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track S. Veikkolainen Intended status: Standards Track S. Veikkolainen
Expires: June 20, 2013 Nokia Expires: July 13, 2013 Nokia
December 17, 2012 January 9, 2013
Session Description Protocol (SDP) Extension For Setting Up Audio and Session Description Protocol (SDP) Extension For Setting Up Audio and
Video Media Streams Over Circuit-Switched Bearers In The Public Switched Video Media Streams Over Circuit-Switched Bearers In The Public Switched
Telephone Network (PSTN) Telephone Network (PSTN)
draft-ietf-mmusic-sdp-cs-15 draft-ietf-mmusic-sdp-cs-16
Abstract Abstract
This memo describes use cases, requirements, and protocol extensions This memo describes use cases, requirements, and protocol extensions
for using the Session Description Protocol (SDP) Offer/Answer model for using the Session Description Protocol (SDP) Offer/Answer model
for establishing audio and video media streams over circuit-switched for establishing audio and video media streams over circuit-switched
bearers in the Public Switched Telephone Network (PSTN). bearers in the Public Switched Telephone Network (PSTN).
Status of this Memo Status of this Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 20, 2013. This Internet-Draft will expire on July 13, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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o The Calling Party Number information element in the circuit- o The Calling Party Number information element in the circuit-
switched signaling might not be available, e.g., due to policy switched signaling might not be available, e.g., due to policy
restrictions of the network operator or caller restriction due to restrictions of the network operator or caller restriction due to
privacy. privacy.
o The Calling Party Number information element in the circuit- o The Calling Party Number information element in the circuit-
switched signaling might be available, but the digit switched signaling might be available, but the digit
representation of the E.164 number might differ from the one representation of the E.164 number might differ from the one
expressed in the SDP. To mitigate this problem implementations expressed in the SDP. To mitigate this problem implementations
should consider only some of the rightmost digits from the E.164 should consider only some of the rightmost digits from the E.164
number for correlation. For example, the numbers +44-113-469-0123 number for correlation. For example, the numbers +44-113-496-0123
and 0113-469-0123 could be considered as the same number. This is and 0113-496-0123 could be considered as the same number. This is
also the behavior of some cellular phones, which correlate the also the behavior of some cellular phones, which correlate the
incoming calling party with a number stored in the phone book, for incoming calling party with a number stored in the phone book, for
the purpose of displaying the caller's name. the purpose of displaying the caller's name.
5.2.3.3. User-User Information Element Correlation Mechanism 5.2.3.3. User-User Information Element Correlation Mechanism
A second correlation mechanism is based on including in SDP a string A second correlation mechanism is based on including in SDP a string
that represents the User-User Information Element that is part of the that represents the User-User Information Element that is part of the
call setup signaling of the circuit-switched bearer. The User-User call setup signaling of the circuit-switched bearer. The User-User
Information Element is specified in ITU-T Q.931 [ITU.Q931.1998] and Information Element is specified in ITU-T Q.931 [ITU.Q931.1998] and
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endpoint when establishing the PSTN call, and he also includes the endpoint when establishing the PSTN call, and he also includes the
"a=cs-correlation" attribute line containing the values he is going "a=cs-correlation" attribute line containing the values he is going
to include in the Calling Party Number and User-User IE of the PSTN to include in the Calling Party Number and User-User IE of the PSTN
call establishment. call establishment.
v=0 v=0
o=- 2890973824 2890987289 IN IP4 192.0.2.7 o=- 2890973824 2890987289 IN IP4 192.0.2.7
s= s=
t=0 0 t=0 0
m=audio 9 PSTN - m=audio 9 PSTN -
c=PSTN E164 +441134690124 c=PSTN E164 +441134960124
a=setup:active a=setup:active
a=connection:new a=connection:new
a=cs-correlation:callerid:+441134690124 \ a=cs-correlation:callerid:+441134960124 \
uuie:56A390F3D2B7310023 uuie:56A390F3D2B7310023
Figure 5: SDP Answer with circuit-switched media Figure 5: SDP Answer with circuit-switched media
When Alice receives the Answer, she examines that Bob is willing to When Alice receives the Answer, she examines that Bob is willing to
become the active endpoint when setting up the PSTN call. Alice become the active endpoint when setting up the PSTN call. Alice
temporarily stores Bob's E.164 number and the User-User IE value of temporarily stores Bob's E.164 number and the User-User IE value of
the "cs-correlation" attribute, and waits for a circuit-switched the "cs-correlation" attribute, and waits for a circuit-switched
bearer establishment. bearer establishment.
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Upon receiving the SDP offer described in Figure 7, Bob rejects the Upon receiving the SDP offer described in Figure 7, Bob rejects the
video stream as his device does not currently support video, but video stream as his device does not currently support video, but
accepts the circuit-switched audio stream. As Alice indicated that accepts the circuit-switched audio stream. As Alice indicated that
she is able to become either the active, or passive party, Bob gets she is able to become either the active, or passive party, Bob gets
to select which role he would like to take. Since the Offer to select which role he would like to take. Since the Offer
contained the international E.164 number of Alice, Bob decides that contained the international E.164 number of Alice, Bob decides that
he becomes the active party in setting up the circuit-switched he becomes the active party in setting up the circuit-switched
bearer. Bob includes a new value in the "dtmf" subfield of the "cs- bearer. Bob includes a new value in the "dtmf" subfield of the "cs-
correlation" attribute, which he is going to send as DTMF tones once correlation" attribute, which he is going to send as DTMF tones once
the bearer setup is complete. For the video bearer, caller ID based the bearer setup is complete. The Answer is described in Figure 8
correlation is used. The Answer is described in Figure 8
v=0 v=0
o=- 2890973824 2890987289 IN IP4 192.0.2.7 o=- 2890973824 2890987289 IN IP4 192.0.2.7
s= s=
t=0 0 t=0 0
a=setup:active a=setup:active
a=connection:new a=connection:new
c=PSTN E164 +441134690124 c=PSTN E164 +441134960124
m=audio 9 PSTN - m=audio 9 PSTN -
a=cs-correlation:dtmf:654321 a=cs-correlation:dtmf:654321
m=video 0 PSTN 34 m=video 0 PSTN 34
a=cs-correlation:dtmf:+441134690124 a=cs-correlation:callerid:+441134960124
Figure 8: SDP answer with circuit-switched audio and video (2) Figure 8: SDP answer with circuit-switched audio and video (2)
7. Security Considerations 7. Security Considerations
This document provides an extension on top of RFC 4566 [RFC4566], and This document provides an extension on top of RFC 4566 [RFC4566], and
RFC 3264 [RFC3264]. As such, the security considerations of those RFC 3264 [RFC3264]. As such, the security considerations of those
documents apply. documents apply.
This memo provides mechanisms to agree on a correlation identifier or This memo provides mechanisms to agree on a correlation identifier or
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Type SDP Name Reference Type SDP Name Reference
-------------- --------------------------- --------- -------------- --------------------------- ---------
proto PSTN [RFCxxxx] proto PSTN [RFCxxxx]
The related "fmt" namespace re-uses the conventions and payload type The related "fmt" namespace re-uses the conventions and payload type
number defined for RTP/AVP. In this document, the RTP audio and number defined for RTP/AVP. In this document, the RTP audio and
video media types, when applied to PSTN circuit-switched bearers, video media types, when applied to PSTN circuit-switched bearers,
represent merely an audio or video codec in its native format represent merely an audio or video codec in its native format
directly on top of a single PSTN bearer. directly on top of a single PSTN bearer.
In come cases, the endpoint is not able to determine the lsit of In come cases, the endpoint is not able to determine the list of
available codecs for circuit-switched media streams. In this case, available codecs for circuit-switched media streams. In this case,
in order to be syntactically compliant with SDP [RFC4566], the in order to be syntactically compliant with SDP [RFC4566], the
endpoint MUST include a single dash ("-") in the <fmt> subfield.
9. Acknowledgments 9. Acknowledgments
The authors want to thank Paul Kyzivat, Flemming Andreasen, Thomas The authors want to thank Paul Kyzivat, Flemming Andreasen, Thomas
Belling, John Elwell, Jari Mutikainen, Miikka Poikselka, Jonathan Belling, John Elwell, Jari Mutikainen, Miikka Poikselka, Jonathan
Rosenberg, Ingemar Johansson, Christer Holmberg, Alf Heidermark, Tom Rosenberg, Ingemar Johansson, Christer Holmberg, Alf Heidermark, Tom
Taylor, Thomas Belling, Keith Drage, and Andrew Allen for providing Taylor, Thomas Belling, Keith Drage, and Andrew Allen for providing
their insight and comments on this document. their insight and comments on this document.
10. References 10. References
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