draft-ietf-ecrit-phonebcp-00.txt   draft-ietf-ecrit-phonebcp-01.txt 
ecrit B. Rosen ecrit B. Rosen
Internet-Draft NeuStar Internet-Draft NeuStar
Intended status: Standards Track J. Polk Intended status: Standards Track J. Polk
Expires: April 18, 2007 Cisco Systems Expires: September 6, 2007 Cisco Systems
October 15, 2006 March 05, 2007
Best Current Practice for Communications Services in support of Best Current Practice for Communications Services in support of
Emergency Calling Emergency Calling
draft-ietf-ecrit-phonebcp-00.txt draft-ietf-ecrit-phonebcp-01.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 18, 2007. This Internet-Draft will expire on September 6, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
Abstract Abstract
Requesting help in an emergency using a communications device such as Requesting help in an emergency using a communications device such as
a telephone or mobile is an accepted practice in most of the world. a telephone or mobile is an accepted practice in most of the world.
As communications devices increasingly utilize the Internet to As communications devices increasingly utilize the Internet to
interconnect and communicate, users will continue to expect to use interconnect and communicate, users will continue to expect to use
such devices to request help, regardless of whether or not they such devices to request help, regardless of whether or not they
communicate using IP. The emergency response community will have to communicate using IP. The emergency response community will have to
upgrade their facilities to support the wider range of communications upgrade their facilities to support the wider range of communications
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and service capability. The IETF has several efforts targeted at and service capability. The IETF has several efforts targeted at
standardizing various aspects of placing emergency calls. This memo standardizing various aspects of placing emergency calls. This memo
describes best current practice on how devices and services should describes best current practice on how devices and services should
use such standards to reliably make emergency calls use such standards to reliably make emergency calls
Table of Contents Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Which devices and services should support emergency calls . . 4 3. Which devices and services should support emergency calls . . 4
4. Determining Location . . . . . . . . . . . . . . . . . . . . . 4 4. Location . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Endpoints learn their own location . . . . . . . . . . . . 5
4.2. Location Configuration Protocols . . . . . . . . . . . . . 5
4.3. Self reported Location . . . . . . . . . . . . . . . . . . 6
4.4. When Location should be Configured . . . . . . . . . . . . 6
4.5. Other location considerations . . . . . . . . . . . . . . 7
5. Determining an emergency call . . . . . . . . . . . . . . . . 7 5. Determining an emergency call . . . . . . . . . . . . . . . . 7
6. Session Signaling . . . . . . . . . . . . . . . . . . . . . . 8 6. Session Signaling . . . . . . . . . . . . . . . . . . . . . . 9
6.1. SIP signaling requirements for User Agents . . . . . . . . 8 6.1. SIP signaling requirements for User Agents . . . . . . . . 9
6.2. Mapping from Location to a PSAP URI . . . . . . . . . . . 9 6.2. SIP signaling requirements for proxy servers and B2BUAs . 10
6.3. Routing the call . . . . . . . . . . . . . . . . . . . . . 10 6.3. Mapping from Location to a PSAP URI . . . . . . . . . . . 11
6.4. Responding to PSAP signaling . . . . . . . . . . . . . . . 10 6.4. Routing the call . . . . . . . . . . . . . . . . . . . . . 12
6.5. Disabling of features . . . . . . . . . . . . . . . . . . 11 6.5. Responding to PSAP signaling . . . . . . . . . . . . . . . 12
7. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.6. Disabling of features . . . . . . . . . . . . . . . . . . 13
7.1. Testing Mechanism . . . . . . . . . . . . . . . . . . . . 11 7. Location Update . . . . . . . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9. Normative References . . . . . . . . . . . . . . . . . . . . . 12 9. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1. Testing Mechanism . . . . . . . . . . . . . . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . . . . 16 10. Security Considerations . . . . . . . . . . . . . . . . . . . 15
10.1. Threats against endpoints . . . . . . . . . . . . . . . . 15
10.2. Threats against the Emergency Service . . . . . . . . . . 16
11. Normative References . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
Intellectual Property and Copyright Statements . . . . . . . . . . 21
1. Requirements notation 1. Requirements notation
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 this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Introduction 2. Introduction
This document describes how SIP User Agents and proxy servers support This document describes how SIP User Agents and proxy servers support
emergency calling, as outlined in [framework]. Here, an emergency emergency calling, as outlined in [I-D.ietf-ecrit-framework]. Here,
call refers to a communications session established by a user to a an emergency call refers to a communications session established by a
"Public Safety Answering Point" (PSAP) which is a call center user to a "Public Safety Answering Point" (PSAP) which is a call
established by response agencies to accept emergency calls. We center established by response agencies to accept emergency calls.
differentiate such calls from other sessions which are created by We differentiate such calls from other sessions which are created by
responders using public communications infrastructure often involving responders using public communications infrastructure often involving
some kind of priority access as defined in Emergency some kind of priority access as defined in Emergency
Telecommunications Service (ETS) in IP Telephony [RFC4190]. Telecommunications Service (ETS) in IP Telephony [RFC4190]. By
implication, this document describes the interface between the
emergency services network and the Internet. This memo also
describes how location may be obtained from the local access
infrastructure (broadband network), and thus specifies requirements
to support location in such infrastructure.
Making an emergency call involves the use of location information, Making an emergency call involves the use of location information,
referring to the physical location of the caller. Location is used referring to the physical location of the caller. Location is used
within the emergency calling system to route a call to the correct within the emergency calling system to route a call to the correct
PSAP, as well as by the PSAP to choose the correct responder, and PSAP, as well as by the PSAP to choose the correct responder, and
direct them to the person in need of assistance. direct them to the person in need of assistance.
The steps involved in an emergency call from an IP based device are The steps involved in an emergency call from an IP based device are
(with a rough ordering of operation) (with a rough ordering of operation)
1. Device connects to access network, and obtains initial location 1. Device connects to access network, and obtains initial location
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4. User device includes location indication (by value or by 4. User device includes location indication (by value or by
reference) in the call set-up messaging reference) in the call set-up messaging
5. emergency call set-up is routed to appropriate PSAP based on 5. emergency call set-up is routed to appropriate PSAP based on
location of the caller location of the caller
6. call is established with PSAP 6. call is established with PSAP
7. caller's location is presented to PSAP operator for dispatch 7. caller's location is presented to PSAP operator for dispatch
As a quick overview for a typical Ethernet connected telephone using As a quick overview for a typical Ethernet connected telephone using
SIP signaling: SIP signaling:
o the phone "boots" and connects to its access network o the phone "boots" and connects to its access network
o the phone would get location from the DHCP server [or an L7 o the phone would get location from the DHCP server [an L7 server]
server]. or the first level switch's LLDP server.
o It would use "urn:service:sos" as the URI of an emergency call.
o the phone obtains the local emergency dialstring(s) from the
[I-D.ietf-ecrit-lost] server.
o It recognizes an emergency call from the dialstrings and uses
"urn:service:sos" to mark an emergency call.
o It would determine the PSAP's URI by using the o It would determine the PSAP's URI by using the
[I-D.ietf-ecrit-lost] mapping server from the location provided in [I-D.ietf-ecrit-lost] mapping server from the location provided
the signaling
o It would put its location in the SIP INVITE as a PIDF-LO in the o It would put its location in the SIP INVITE as a PIDF-LO in the
body of the INVITE (or a reference to location in a Location body of the INVITE (or a reference to location in a Location
header) and forward the call to its first hop proxy. header) [I-D.ietf-sip-location-conveyance] and forward the call to
its first hop proxy.
o The proxy recognizes the call as an emergency call and routes the o The proxy recognizes the call as an emergency call and routes the
call using normal SIP routing mechanisms call using normal SIP routing mechanisms.
[RFC4504] details Best Current Practice for SIP user agents. This o The call is established and common media streams opened.
memo can be considered an addition to it for endpoints.
Best Current Practice for SIP user agents including handling of audio
and real-time text [RFC4103]media detailed in [RFC4504] SHOULD be
applied. This memo can be considered an addition to it for
endpoints.
3. Which devices and services should support emergency calls 3. Which devices and services should support emergency calls
Although present PSAPs have only support for voice calls placed Support for voice calls and real-time text calls placed through PSTN
through PSTN facilities or systems connected to the PSTN, future facilities or systems connected to the PSTN is found in present
PSAPs will support Internet connectivity and a wider range of media PSAPs. Future PSAPs will however support Internet connectivity and a
types. In general, if a user could reasonably expect to be able to wider range of media types and provide higher functionality.. In
call for help with the device, then the device or service should general, if a user could reasonably expect to be able to call for
support emergency calling. Certainly, any device or service that help with the device, then the device or service should support
looks like and works like a telephone (wired or mobile) should emergency calling. Certainly, any device or service that looks like
support emergency calling, but increasingly, users have expectations and works like a telephone (wired or mobile) should support emergency
that other devices and services should work. calling, but increasingly, users have expectations that other devices
and services should work.
Using current (evolving) standards, devices that create media Using current (evolving) standards, devices that create media
sessions and exchange audio, video and/or text, and have the sessions and exchange audio, video and/or text, and have the
capability to establish sessions to a wide variety of addresses, and capability to establish sessions to a wide variety of addresses, and
communicate over private IP networks or the Internet, should support communicate over private IP networks or the Internet, should support
emergency calls. emergency calls.
4. Determining Location 4. Location
Location is central to the operation of emergency services. Location
is used to route a call to the PSAP that serves the location, and it
is used to dispatch responders to the person in need of help. It is
frequently the case that the user in an emergency is unable to
provide a unique, valid location themselves. For this reason,
automatic location is the norm.
In Internet emergency calling, we "Determine" where the endpoint is
located using a variety of measurement or wiretracing methods. We
"Configure" endpoints with their own location. We "Map" the location
to the URI to send the call to, and we "Convey" the location to the
PSAP (and other elements) in the signaling. These topics are
detailed in [I-D.ietf-ecrit-framework].
4.1. Endpoints learn their own location
With Internet based communications services, determining where the With Internet based communications services, determining where the
caller is located is more problematic than in PSTN and mobile caller is located is more problematic than in PSTN and mobile
systems. Existing wired phones are tethered with a wire that is systems. Existing wired phones are tethered with a wire that is
connected directly to a call control device, a circuit switch. connected directly to a call control device, a circuit switch.
Cellular phones are tethered via a radio channel to a cell tower, Cellular phones are tethered via a radio channel to a cell tower,
which connects that cell phone to a circuit switch. The primary which connects that cell phone to a circuit switch. The primary
difficulty with IP based phones is that the connectivity, whether difficulty with IP based phones is that the connectivity, whether
wired or radio channel, is decoupled from the call control device. wired or radio channel, is decoupled from the call control device.
The communications service may not have any relationship with the The communications service may not have any relationship with the
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way to even find out who the access carrier is. way to even find out who the access carrier is.
For this reason, standards have been created for endpoints (devices) For this reason, standards have been created for endpoints (devices)
to obtain location information where it is the access network that to obtain location information where it is the access network that
knows the location of the endpoint. To obtain location information, knows the location of the endpoint. To obtain location information,
the endpoint can use a Location Configuration Protocol. The endpoint the endpoint can use a Location Configuration Protocol. The endpoint
is a subscriber to both the access network and the communications is a subscriber to both the access network and the communications
service, and thus is in a position to obtain its location from the service, and thus is in a position to obtain its location from the
access network, and supply it to the communications service. These access network, and supply it to the communications service. These
issues, and the necessity for endpoints and access networks to issues, and the necessity for endpoints and access networks to
support LCPs is detailed in [framework]. support LCPs is detailed in [I-D.ietf-ecrit-framework].
4.2. Location Configuration Protocols
For devices that operate on a network where the network operator For devices that operate on a network where the network operator
controls the specification of every device connected to that network controls the specification of every device connected to that network
that could be used for emergency calls, the method by which location that could be used for emergency calls, the method by which location
is determined need not be an IETF standard, but can be any method is determined need not be an IETF standard, but can be any method
that achieves the desired result. Such a method MUST be specified, that achieves the desired result. Such a method MUST be specified,
and every device MUST support it. and every device MUST support it. It is recommended that, in
addition, the network SHOULD support one or more of DHCP,
[Placeholder for L7 LCP} or LLDP-MED.
For all other devices, location configuration by DHCP, [Placeholder For all other devices, the device MUST support DHCP, [Placeholder for
for L7 LCP] and LLDP-MED MUST be supported. DHCP [RFC2131] has been L7 LCP] and LLDP-MED. The access network MUST support at least one
enhanced to provide the location of a device. [RFC3825] describes of these.
how a geo-location (lat/lon/alt) may be obtained and
[I-D.schulzrinne-geopriv-dhcp-civil] describes how a civic (street
address) location can be obtained via DHCP.
[Placeholder for HELD, LCP or other L7 location determination DHCP [RFC2131] has been enhanced to provide the location of a device.
[RFC3825] describes how a geo-location (lat/lon/alt) may be obtained
and [RFC4676] describes how a civic (street address) location can be
obtained via DHCP.
[Placeholder for HELD, RELO or other L7 location determination
methods] methods]
[LLDP] with [LLDP-MED] extensions provides an alternative to DHCP in [LLDP] with [LLDP-MED] extensions provides location configuration
many enterprise environments. applicable in many enterprise environments.
For devices that operate in a network where the network operator For devices that operate in a network where the network operator
controls the specification of every device connected to that network, controls the specification of every device connected to that network,
but the network attachment supports upstream networks to which but the network attachment supports upstream networks to which
communications devices are connected (such as any network that communications devices are connected (such as any network that
supports Ethernet connected telephones and terminal adapters), the supports Ethernet connected telephones and terminal adapters), the
method by which location is determined need not be an IETF standard, method by which location is determined need not be an IETF standard,
but can be any method which achieves the desired result. However, but can be any method which achieves the desired result. However,
the network attachment MUST support at least one of DHCP [L7 LCP] or the network attachment MUST support at least one of DHCP [L7 LCP] or
LLDP-MED for upstream communications devices to obtain location. For LLDP-MED for upstream communications devices to obtain location. For
smaller interior (e.g, LAN) networks, the DHCP, [L7 LCP] or LLDP-MED smaller interior (e.g, LAN) networks, the DHCP, [L7 LCP] or LLDP-MED
server should simply repeat the location obtained from the access server should simply repeat the location obtained from the access
network. For larger networks, other mechanisms, such as a DHCP Relay network. For larger networks, other mechanisms, such as a DHCP Relay
Agent [RFC3046] SHOULD be used to provide more accurate location of Agent [RFC3046] SHOULD be used to provide more accurate location of
endpoints. endpoints.
For devices that operate on a network where the network operator does 4.3. Self reported Location
not control the specification of every device connected to the
network, at least one of DHCP, [L7 LCP] or LLDP-MED MUST be supported
on the network.
Self Reported location is generally unacceptable in emergency calls, Self reported location, where a user enters location himself, is
although it is being used prior to automatic location determination generally unacceptable in emergency calls, although it is being used
schemes being fielded. Local laws may govern what is acceptable in prior to automatic location determination schemes being fielded.
any country or area. Devices and/or access networks SHOULD support a Local laws may govern what is acceptable in any country or area.
manual method to "override" the location the access network Devices and/or access networks SHOULD support a manual method to
determines. The access network generally only knows the location of "override" the location the access network determines. The access
its demarcation point between the access network and the subscriber. network generally only knows the location of its demarcation point
The subscriber could have an extended network behind the demarc between the access network and the subscriber. The subscriber could
unknown to the access network. A method to account for this have an extended network behind the demarc unknown to the access
condition SHOULD be provided. network. A method to account for this condition SHOULD be provided.
4.4. When Location should be Configured
Devices SHOULD get location immediately after obtaining local network Devices SHOULD get location immediately after obtaining local network
configuration information. It is essential for the location to be configuration information. It is essential for the location to be
determined BEFORE any VPN tunnels are established. It is equally determined BEFORE any VPN tunnels are established. It is equally
essential that this location information is *not* overwritten by any essential that this location information is *not* overwritten by any
process engaged from establishing a VPN connection. In other words, process engaged from establishing a VPN connection. In other words,
the established VPN to Chicago from the device in Dallas should not the established VPN to Chicago from the device in Dallas MUST NOT
overwrite the Dallas location for any reason especially an emergency overwrite the Dallas location for any reason especially an emergency
call. call.
It is desirable that location information be periodically refreshed. It is desirable that location information be periodically refreshed.
For devices which are not expected to roam, refreshing on the order For devices which are not expected to roam, refreshing on the order
of once per day is RECOMMENDED. For devices which roam, refresh of of once per day is RECOMMENDED. For devices which roam, refresh of
location SHOULD be more frequent, with the frequency related to the location SHOULD be more frequent, with the frequency related to the
mobility of the device and the ability of the access network to mobility of the device and the ability of the access network to
support the refresh operation. There can be instances in which a support the refresh operation. There can be instances in which a
device is aware of when it moves, for example when it changes access device is aware of when it moves, for example when it changes access
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systems should ideally be designed such that the typical response is systems should ideally be designed such that the typical response is
under 100ms. These numbers are empirically derived, but are intended under 100ms. These numbers are empirically derived, but are intended
to keep total call signaling time below 2 seconds. There are to keep total call signaling time below 2 seconds. There are
conflicts between the time it takes to generate location when conflicts between the time it takes to generate location when
measuring techniques are used and the desire to route the call measuring techniques are used and the desire to route the call
quickly. If an accurate location cannot be determined quickly, a quickly. If an accurate location cannot be determined quickly, a
rough location SHOULD be returned within 100ms which can be used to rough location SHOULD be returned within 100ms which can be used to
route the call. The location of the nearest base station in a route the call. The location of the nearest base station in a
wireless network is an example of a rough location. wireless network is an example of a rough location.
4.5. Other location considerations
If the LCP does not return location in the form of a PIDF-LO If the LCP does not return location in the form of a PIDF-LO
[RFC4119], the endpoint must map the location information it receives [RFC4119], the endpoint MUST map the location information it receives
from the configuration protocol to a PIDF-LO. from the configuration protocol to a PIDF-LO.
To prevent against spoofing of the DHCP server, devices implementing
DHCP for location configuration SHOULD use [RFC3118].
5. Determining an emergency call 5. Determining an emergency call
An emergency call is distinguished by the device (or a downstream An emergency call is distinguished by the device (or a downstream
element) by an "address", which in most cases for Internet connected element) by an "address", which in most cases for Internet connected
devices is still a dialstring, although other user interfaces may be devices is still a dialstring, although other user interfaces may be
used. used.
Note: It is undesirable to have a single "button" emergency call user Note: It is undesirable to have a single "button" emergency call user
interface element. These mechanisms have a very high false call interface element. These mechanisms have a very high false call
rate. PSAPs prefer devices to use their local emergency call rate. PSAPs prefer devices to use their local emergency call
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While in some countries there is a single 3 digit dialstring that is While in some countries there is a single 3 digit dialstring that is
used for all emergency calls (i.e. 911 in North America), in some used for all emergency calls (i.e. 911 in North America), in some
countries there are several 3 digit numbers used for different types countries there are several 3 digit numbers used for different types
of calls. For example, in Switzerland, 117 is used to call police, of calls. For example, in Switzerland, 117 is used to call police,
118 is used to call the fire brigade, and 144 is used for emergency 118 is used to call the fire brigade, and 144 is used for emergency
medical assistance. In other countries, there are no "short codes" medical assistance. In other countries, there are no "short codes"
or "service codes" for 3 digit dialing of emergency services and or "service codes" for 3 digit dialing of emergency services and
local (PSTN) numbers are used. local (PSTN) numbers are used.
[I-D.schulzrinne-sipping-service] introduces a universal emergency [I-D.ietf-ecrit-service-urn] introduces a universal emergency service
service URN scheme. On the wire, emergency calls SHOULD include this URN scheme. On the wire, emergency calls SHOULD include this type of
type of URI as a Route header [RFC3261]. The scheme includes a URI as a Route header [RFC3261]. The scheme includes a single
single emergency URN (urn:service:sos) and responder specific ones emergency URN (urn:service:sos) and responder specific ones
(urn:service:sos.police). Using the service:sos URN scheme, (urn:service:sos.police). Using the service:sos URN scheme,
emergency calls can be recognized as such throughout the Internet. emergency calls can be recognized as such throughout the Internet.
Devices MUST use the service:sos URN scheme to mark emergency calls. Devices MUST use the service:sos URN scheme to mark emergency calls.
To determine which calls are emergency calls, some entity needs to To determine which calls are emergency calls, some entity needs to
map a user entered dialstring into this URN scheme. A user may map a user entered dialstring into this URN scheme. A user may
"dial" 1-1-2, but the call would be sent to urn:service:sos. This "dial" 1-1-2, but the call would be sent to urn:service:sos. This
mapping is SHOULD performed at the endpoint device, but MAY be mapping is SHOULD performed at the endpoint device, but MAY be
performed at an intermediate entity (such as a SIP proxy server). performed at an intermediate entity (such as a SIP proxy server).
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dialstring(s) and map to the universal emergency URN. If devices dialstring(s) and map to the universal emergency URN. If devices
cannot do "dial plan interpretation", then the first signaling aware cannot do "dial plan interpretation", then the first signaling aware
element (first hop proxy in SIP signaled devices) SHOULD do the element (first hop proxy in SIP signaled devices) SHOULD do the
mapping. It is important to not require a large number of active mapping. It is important to not require a large number of active
elements handle a call before it is recognized as an emergency call elements handle a call before it is recognized as an emergency call
In systems that support roaming, there may be a concept of "visited" In systems that support roaming, there may be a concept of "visited"
and "home" networks. Even when there is not a "visited network", the and "home" networks. Even when there is not a "visited network", the
user may be roaming (or nomadic) in a different country from their user may be roaming (or nomadic) in a different country from their
home. This gives rise to the problem of which dialstring(s) to home. This gives rise to the problem of which dialstring(s) to
recognize, the "home" or "visited"? While it is desirable that the recognize, the "home" or "visited"? While the "home" dialstrings
"home" dialstrings be recognized, it is required (by law in some SHOULD be recognized, it is required (by law in some countries) that
countries) that the "visited" dialstrings be recognized. Dial plan the "visited" dialstrings MUST be recognized. "Visited" dialstrings
would be essential if a guest used a roaming phone. Dial plan
interpretation may need to take "visited" emergency dialstrings into interpretation may need to take "visited" emergency dialstrings into
account. account.
To give an example of this difference in dialstrings: If the device To give an example of this difference in dialstrings: If the device
is from North America, the home and visited emergency dialstring is is from North America, the home and visited emergency dialstring is
"9-1-1". If that devices roams to the UK, the home emergency "9-1-1". If that devices roams to the UK, the home emergency
dialstring is still "9-1-1", but the visited emergency dialstring dialstring is still "9-1-1", but the visited emergency dialstring
would become "9-9-9". If the device roams to Paris, the home would become "9-9-9". If the device roams to Paris, the home
dialstring remains the same, "9-1-1", but the visited dialstring dialstring remains the same, "9-1-1", but the visited dialstring
changes from 999 to "1-1-2". changes from 999 to "1-1-2".
The home emergency dialstrings MAY be provisioned into the device (or The home emergency dialstrings MAY be provisioned into the device (or
other element doing dialstring to universal emergency call URN other element doing dialstring to universal emergency call URN
mapping). [I-D.ietf-ecrit-lost]) provides dialstrings for a given mapping). [I-D.ietf-ecrit-lost]) provides dialstrings for a given
location and SHOULD be used by devices to learn the local (i.e. location and SHOULD be used by devices to learn the local (i.e.
"visited" dialstrings. "visited" dialstrings. "Home" dialstrings MAY be learned by
configuration.
6. Session Signaling 6. Session Signaling
SIP signaling [RFC3261] is expected be supported by upgraded PSAPs. SIP signaling [RFC3261] is expected be supported by upgraded PSAPs.
Gateways MAY be used between Internet connected devices and older Gateways MAY be used between Internet connected devices and older
PSAPs. Some countries may support other signaling protocols into PSAPs. Some countries may support other signaling protocols into
PSAPs. PSAPs.
6.1. SIP signaling requirements for User Agents 6.1. SIP signaling requirements for User Agents
The initial signaling Method is INVITE. The initial SIP signaling Method is an INVITE.
1. The Request URI SHOULD be a PSAP URI obtained from LoST (see 1. The Request URI SHOULD be a PSAP URI obtained from LoST (see
Section 6.2). If the device cannot access a LoST server, the Section 6.3). If the device cannot access a LoST server, the
To: SHOULD be a service URN in the "sos" tree. If the device To: SHOULD be a service URN in the "sos" tree. If the device
cannot do local dialstring interpretation, the Request URI: cannot do local dialstring interpretation, the Request-URI
SHOULD be a dialstring URI [I-D.rosen-iptel-dialstring]with the SHOULD be a dialstring URI [I-D.rosen-iptel-dialstring]with the
dialed digits. sips MUST be specified, unless the operation must dialed digits. A sips URI [RFC3261] MUST be specified, unless
be retried due to a failure to establish a TLS connection. the operation must be retried due to a failure to establish a
TLS connection.
2. The To: header MUST be present and SHOULD be a service URN in 2. The To: header MUST be present and SHOULD be a service URN in
the "sos" tree. If the device cannot do local dialstring the "sos" tree. If the device cannot do local dialstring
interpretation, the To: SHOULD be a dialstring URI with the interpretation, the To: SHOULD be a dialstring URI with the
dialed digits. sips MUST be specified, unless the operation must dialed digits. sips MUST be specified, unless the operation must
be retried due to a failure to establish a TLS connection. be retried due to a failure to establish a TLS connection.
3. The From: header MUST be present and SHOULD be the AoR of the 3. The From: header MUST be present and SHOULD be the AoR of the
caller. caller.
NOTE: unintialized devices may not have an AoR available NOTE: unintialized devices may not have an AoR available
4. A Via: header MUST be present and SHOULD include the URI of the 4. A Via: header MUST be present and SHOULD include the URI of the
skipping to change at page 9, line 16 skipping to change at page 9, line 51
5. A Route header SHOULD be present with the service URN in the 5. A Route header SHOULD be present with the service URN in the
"sos" tree, and the loose route parameter. "sos" tree, and the loose route parameter.
6. Either a P-Asserted-Identity [RFC3325] or an Identity header 6. Either a P-Asserted-Identity [RFC3325] or an Identity header
[RFC4474], or both, SHOULD be included to identify the sender. [RFC4474], or both, SHOULD be included to identify the sender.
7. A Contact header MUST be present (which might contain a GRUU 7. A Contact header MUST be present (which might contain a GRUU
[I-D.ietf-sip-gruu]) to permit an immediate call-back to the [I-D.ietf-sip-gruu]) to permit an immediate call-back to the
specific device which placed the emergency call. specific device which placed the emergency call.
8. Other headers MAY be included as per normal sip behavior 8. Other headers MAY be included as per normal sip behavior
9. A Supported: header MUST be included with the 'geolocation' 9. A Supported: header MUST be included with the 'geolocation'
option tag[I-D.ietf-sip-location-conveyance], unless the device option tag[I-D.ietf-sip-location-conveyance], unless the device
does not understand the concept of SIP Location ; does not understand the concept of SIP Location.
10. If the device's location is by-reference, a Geolocation:
header[I-D.ietf-sip-location-conveyance] MUST be present 10. If the device's location is by-reference, a Geolocation: header
containing the URI of the PIDF-LO reference for that device; [I-D.ietf-sip-location-conveyance] MUST be present containing
the URI of the PIDF-LO reference for that device. Whichever
location is used for routing the message towards the PSAP or
ESRP, even if there is only one, the Geolocation "message-
routed-on-this-uri" header parameter SHOULD be added to the
corresponding URI in the Geolocation header.
11. if a device understands the SIP Location Conveyance 11. if a device understands the SIP Location Conveyance
[I-D.ietf-sip-location-conveyance] extension and has its [I-D.ietf-sip-location-conveyance] extension and has its
location available, it MUST include location either by-value or location available, it MUST include location either by-value or
by-reference. If it is by-value, the INVITE contains a by-reference. If it is by-value, the INVITE contains a
Supported header with a "geolocation" option tag, and a "cidURL" Supported header with a "geolocation" option tag, and a "cid-
[RFC2396]as the value in the Geolocation header, indicating URL" [RFC2396] as the value in the Geolocation header,
which message body part contains the PIDF-LO. If the INVITE indicating which message body part contains the PIDF-LO. If the
contains a location by-reference, it includes the same Supported INVITE contains a location by-reference, it includes the same
header with the "geolocation" option tag, and includes the URI Supported header with the "geolocation" option tag, and includes
of the PIDF-LO on a remote node in a Geolocation header. the URI of the PIDF-LO on a remote node in a Geolocation header.
[I-D.ietf-geopriv-pdif-lo-profile] MUST be used [I-D.ietf-geopriv-pdif-lo-profile] MUST be used
12. If a device understand the SIP Location Conveyance extension and 12. If a device understands the SIP Location Conveyance extension
has its location unavailable or unknown to that device, it MUST and has its location unavailable or unknown to that device, it
include a Supported header with a "geolocation" option tag, and MUST include a Supported header with a "geolocation" option tag,
not include a Geoocation header, and not include a PIDF-LO and not include a Geolocation header, and not include a PIDF-LO
message body.; message body.
13. A normal SDP offer SHOULD be included in the INVITE. The offer 13. A normal SDP offer SHOULD be included in the INVITE. The offer
SHOULD NOT include compressed audio codecs, although a wideband MUST include the G.711 codec, see Section 8.
codec offer MAY be included. 14. If the device includes location-by-value, the UA MUST support
multipart message bodies, since SDP will likely be also in the
INVITE.
15. A UAC SHOULD include the Geolocation "inserted-by=endpoint"
header parameter. This informs downstream elements which device
entered the location at this URI (either cid-URL or location-by-
reference URI).
Note: Silence suppression (Voice Activity Detection methods) MUST NOT 6.2. SIP signaling requirements for proxy servers and B2BUAs
be used on emergency calls. PSAP call takers sometimes get
information on what is happening in the background to determine how
to process the call.
6.2. Mapping from Location to a PSAP URI SIP Proxy servers processing emergency calls:
1. If the proxy does dial plan interpretation on behalf of user
agents, the proxy MUST look for the local emergency dialstring at
the location of the end device. If it finds it it MUST:
* Obtain the location (or a reference to it) for the endpoint
* Insert a Geolocation header as per 10-12 above
* Include the Geolocation "inserted-by=server" AND "routed-by-
this-uri" parameters.
* Map the location to a PSAP uri using LoST.
* Add a Route header with the service URN appropriate for the
emergency dialstring.
* Replace the Request-URI (which was the dialstring) with the
PSAP URI obtained from LoST.
* Route the call using normal SIP routing mechanisms.
2. The "inserted-by=" header parameter MUST NOT be modified or
deleted in transit.
3. If a Geolocation "message-routed-on-this-uri" header parameter
exists when a new SIP server processes a message, and the message
is routing is now to be done based on another Geolocation URI
(by-value or by-reference), the "message-routed-on-this-uri"
header parameter MUST be removed from the old Geolocation URI and
inserted with the now applicable location URI in the Geolocation
header.
6.3. Mapping from Location to a PSAP URI
To route an emergency call, we make use of the [I-D.ietf-ecrit-lost] To route an emergency call, we make use of the [I-D.ietf-ecrit-lost]
mapping service which takes a location expressed by a PIDF-LO and mapping service which takes a location expressed by a PIDF-LO and
returns one or more PSAP URIs. The request includes the service URN returns one or more PSAP URIs. The request includes the service URN
which is used to determine which entity should receive the call. which is used to determine which entity should receive the call.
Ideally, mapping from location to the PSAP URI would be accomplished Ideally, mapping from location to the PSAP URI would be accomplished
at the time the emergency call is placed. However, it could be that at the time the emergency call is placed. However, it could be that
when the emergency occurs, the LoST server is unavailable to the when the emergency occurs, the LoST server is unavailable to the
caller, or busy. To guard against that, devices MUST cache a caller, or busy. To guard against that, devices MUST cache a
mapping. The mapping MUST be performed at boot time, and whenever mapping. The mapping MUST be performed at boot time, and whenever
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Devices where location changes SHOULD use this mechanism to maintain Devices where location changes SHOULD use this mechanism to maintain
a desired mapping. a desired mapping.
User agents that can obtain location information MUST perform the User agents that can obtain location information MUST perform the
mapping from location information to PSAP URI using mapping from location information to PSAP URI using
[I-D.ietf-ecrit-lost]. The mapping is performed whenever the UA [I-D.ietf-ecrit-lost]. The mapping is performed whenever the UA
acquires new location information that is outside the bounds of the acquires new location information that is outside the bounds of the
current PSAP coverage region specified in the LoST response or the current PSAP coverage region specified in the LoST response or the
time-to-live value of that response has expired. time-to-live value of that response has expired.
Determining when the device leaves the area provided by the LoST
service can tax small mobile devices. For this reason, the LoST
server SHOULD return a simple (small number of points) polygon for
geo reported location. This can be an enclosing subset of the area
when the reported point is not near an edge, or a smaller edge
section when the reported location is near an edge. Civic location
is uncommon for mobile devices, but reporting that the same mapping
is good within a community name, or even a street, may be very
helpful for WiFi connected devices that roam and obtain civic
location from the AP they are connected to.
All proxies in the outbound path SHOULD recognize emergency calls All proxies in the outbound path SHOULD recognize emergency calls
with a Request URI of the service URN in the "sos" tree. A proxy with a Request URI of the service URN in the "sos" tree. A proxy
recognizing such a call (which indicates that the endpoint understood recognizing such a call (which indicates that the endpoint understood
the call was an emergency call, but was unable to map its location to the call was an emergency call, but was unable to map its location to
a PSAP URI) MUST perform the LoST mapping and retarget the call to a PSAP URI) MUST perform the LoST mapping and retarget the call to
the PSAP URI (the service URN SHOULD remain as a Route header). the PSAP URI (the service URN SHOULD remain as a Route header).
To deal with old user agents that predate this specification and with To deal with old user agents that predate this specification and with
UAs that do not have access to their own location data, proxies that UAs that do not have access to their own location data, proxies that
recognize a call as an emergency call that is not marked as such (see recognize a call as an emergency call that is not marked as such (see
Section 5) or where the Request-URI is a service:sos URN MUST also Section 5) or where the Request-URI is a service:sos URN MUST also
perform this mapping, with the best location it has available for the perform this mapping, with the best location it has available for the
endpoint. The resulting PSAP URI would become the Request URI. endpoint. The resulting PSAP URI would become the Request URI.
6.3. Routing the call 6.4. Routing the call
Normal routing mechanisms for the specified URI should be used. For Normal routing mechanisms for the specified URI should be used. For
SIP signaled devices, the domain of the URI should be extracted, and SIP signaled devices, the domain of the URI should be extracted, and
the DNS consulted for a sip (or sips) SRV. The resulting NAPTR, if the DNS consulted for a sip (or sips) SRV. The resulting NAPTR, if
present, should be used for the FQDN of the server. present, should be used for the FQDN of the server.
6.4. Responding to PSAP signaling 6.5. Responding to PSAP signaling
The PSAP is expected to use normal signaling (e.g. SIP) as per IETF The PSAP is expected to use normal signaling (e.g. SIP) as per IETF
standards. Devices and proxies should expect to: standards. Devices and proxies should expect to:
1. Be REFERed to a conference bridge; PSAPs often include 1. Be REFERed to a conference bridge; PSAPs often include
dispatchers, responders or specialists on a call. dispatchers, responders or specialists on a call.
2. Be REFERed to a secondary PSAP. Some responder's dispatchers are 2. Be REFERed to a secondary PSAP. Some responder's dispatchers are
not located in the primary PSAP. The call may have to be not located in the primary PSAP. The call may have to be
transferred to another PSAP. Most often this will be an attended transferred to another PSAP. Most often this will be an attended
transfer, or a bridged transfer. transfer, or a bridged transfer.
3. (For devices that are Mobile) SUBSCRIBE to the Presence of the 3. (For devices that are Mobile) SUBSCRIBE to the Presence of the
AoR (or equivalent for other signaling schemes) to get location AoR (or equivalent for other signaling schemes) to get location
updates. updates.
4. Support Session Timer (or equivalent) to guard against session 4. Support Session Timer (or equivalent) to guard against session
corruption corruption
Devices with an active emergency call (i.e. SIP Dialog) MUST NOT Devices with an active emergency call (i.e. SIP Dialog) MUST NOT
generate a BYE request (or equivalent for other non-SIP signaling). generate a BYE request (or equivalent for other non-SIP signaling).
The PSAP must be the only entity that can terminate a call. If the The PSAP must be the only entity that can terminate a call. If the
user "hangs up" an emergency call, the device should ring, and when user "hangs up" an emergency call, the device should ring, and when
skipping to change at page 11, line 25 skipping to change at page 13, line 7
answered, reconnect the caller to the PSAP. answered, reconnect the caller to the PSAP.
There can be a case where the session signaling path is lost, and the There can be a case where the session signaling path is lost, and the
user agent does not receive the BYE. If the call is hung up, the user agent does not receive the BYE. If the call is hung up, the
session timer expires, and 5 minutes elapses from the last message session timer expires, and 5 minutes elapses from the last message
received by the device from the PSAP, the call may be declared lost. received by the device from the PSAP, the call may be declared lost.
If in the 5 minute interval an incoming call is received from the If in the 5 minute interval an incoming call is received from the
domain of the PSAP, the device should drop the old call and alert for domain of the PSAP, the device should drop the old call and alert for
the (new) incoming call. the (new) incoming call.
6.5. Disabling of features 6.6. Disabling of features
The calling device and/or service SHOULD disable outgoing call The calling device and/or service SHOULD disable outgoing call
features such as: features such as:
o Call Waiting o Call Waiting
o Call Transfer o Call Transfer
o Three Way Call o Three Way Call
o Flash hold o Flash hold
o Outbound Call Blocking o Outbound Call Blocking
The emergency dialstrings SHOULD NOT be permitted in Call Forward The emergency dialstrings SHOULD NOT be permitted in Call Forward
numbers or speed dial lists. numbers or speed dial lists.
The device and/or service SHOULD disable the following incoming call The device and/or service SHOULD disable the following incoming call
features on calls from the PSAP: features on calls from the PSAP:
o Call Waiting (all kinds) o Call Waiting (all kinds)
o Do Not Disturb o Do Not Disturb
o Call Forward (all kinds) (if the PSAP calls back within some o Call Forward (all kinds) (if the PSAP calls back within some
(30min?) interval) (30min) interval)
7. Testing 7. Location Update
7.1. Testing Mechanism Devices which are mobile may not be able to report an accurate
location when an emergency call is placed. Some deployments of
location measurement are not always on, and when an emergency call is
initiated, the time to get an accurate "first fix" may be several
seconds. That is too long to wait to begin processing of the call.
In such cases, a fast fix, or the location of a tower serving a
wireless mobile device may be used to route the call, with accurate
location coming later on, after the call is answered. It is possible
that the PSAP that should handle the call once the accurate location
is available is different from the PSAP serving the tower or the
first fix location.
Mobile devices may be moving while an emergency call is in progress.
The PSAPs, and/or the responders may change as the location changes.
For these reasons, and others, update of location is needed.
Generally, updates should occur after the call is completed. The
PSAP controls location update. For calls sent with location-by-
value, the PSAP MAY reINVITE the endpoint and the 200 OK from the
endpoint MUST include the location. For calls send with location-by-
reference, with a SIP or SIPS scheme, the server resolving the
reference MUST support a SUBSCRIBE [RFC3118] to the presence event
[RFC3856]. For other location-by-reference schemes, a repeated
location dereference by the PSAP MUST be supported.
8. Media
Endpoints MUST send and receive media streams on RTP [RFC3550].
Traditionally, voice has been the only media stream accepted by
PSAPs. In some countries, text, in the form of BAUDOT codes or
similar tone encoded signaling within a voiceband is accepted ("TTY")
for persons who have hearing disabilities. With the Internet comes a
wider array of potential media which a PSAP should accept. Using SIP
signaling includes the capability to negotiate media. Normal SIP
offer/answer [RFC3264] negotiations MUST be used to agree on the
media streams to be used.
Endpoints supporting voice MUST support G.711 A law (and mu Law in
North America) encoded voice as described in [RFC3551]. It is
desirable to support wideband codecs in the offer Silence suppression
(Voice Activity Detection methods) MUST NOT be used on emergency
calls. PSAP call takers sometimes get information on what is
happening in the background to determine how to process the call.
Newer text forms are rapidly appearing, with Instant Messaging now
very common, endpoints supporting IM MUST support either [RFC3428] or
[RFC3920]. Endpoints supporting real-time text MUST use [RFC4103].
The expectations for emergency service support for the real-time text
medium, described in [I-D.ietf-sipping-toip], section 7.1 SHOULD be
fulfilled.
Video may be important to support Video Relay Service (Sign language
interpretation) as well as modern video phones. Endpoints supporting
video MUST support H.264 per [RFC3984].
9. Testing
9.1. Testing Mechanism
INVITE requests to a service urn with a urn parameter of "test" INVITE requests to a service urn with a urn parameter of "test"
indicates a request for an automated test. For example, indicates a request for an automated test. For example,
"urn:service.sos.fire;test". As in standard SIP, a 200 (OK) response "urn:service.sos.fire;test". As in standard SIP, a 200 (OK) response
indicates that the address was recognized and a 404 (Not found) that indicates that the address was recognized and a 404 (Not found) that
it was not. A 486 (Busy Here) should be returned if the test service it was not. A 486 (Busy Here) MUST be returned if the test service
is busy, and a 488 (Not Acceptable Here) should be returned if the is busy, and a 488 (Not Acceptable Here) MUST be returned if the PSAP
PSAP does not support the test mechanism. does not support the test mechanism.
In its response to the test, the PSAP MAY include a text body In its response to the test, the PSAP MAY include a text body
indicating the identity of the PSAP, the requested service, and the indicating the identity of the PSAP, the requested service, and the
location reported with the call. For the latter, the PSAP SHOULD location reported with the call. For the latter, the PSAP SHOULD
return location-by-value even if the original location delivered with return location-by-value even if the original location delivered with
the test was by-reference. the test was by-reference.
A PSAP accepting a test call SHOULD accept a media loopback A PSAP accepting a test call SHOULD accept a media loopback
test[I-D.ietf-mmusic-media-loopback] and SHOULD support the "rtp-pkt- test[I-D.ietf-mmusic-media-loopback] and SHOULD support the "rtp-pkt-
loopback" and "rtp-start-loopback" options. The user agent would loopback" and "rtp-start-loopback" options. The user agent would
skipping to change at page 12, line 35 skipping to change at page 15, line 29
After an initial IP address assignment test, a full test SHOULD be After an initial IP address assignment test, a full test SHOULD be
repeated approximately every 30 days with a random interval. repeated approximately every 30 days with a random interval.
User agents MUST NOT place a test call immediately after booting, as User agents MUST NOT place a test call immediately after booting, as
a widespread power outage and subsequent restoration would impose an a widespread power outage and subsequent restoration would impose an
inordinate load on the emergency call routing system. inordinate load on the emergency call routing system.
PSAPs MAY refuse repeated requests for test from the same device in a PSAPs MAY refuse repeated requests for test from the same device in a
short period of time. short period of time.
8. Security Considerations 10. Security Considerations
There are no new security considerations beyond those in the There are no new security considerations beyond those in the
normative references. This memo does not introduce any new normative references. This memo does not introduce any new
protocols; it specifies use of several of them. Implementers are protocols; it specifies use of several of them.
admonished to ,,,
9. Normative References 10.1. Threats against endpoints
The largest threat against the endpoint is inadvertent disclosure of
its location. The endpoint acquires location from a Location
Configuration Protocol. Some of the protocols are very limited as to
the scope which messages within the protocol are distributed. DHCP
for example is limited to the local subnet. LLDP is limited to the
link. The [L7 LCP] is not limited and TLS SHOULD be used to protect
location privacy.
The location configuration server could be spoofed, thus providing
wrong location, and misdirecting help when an emergency call is
placed. When DHCP is the LCP [RFC3118] SHOULD be used to prevent
spoofing if possible. LLDP server spoofing would be limited to
devices connected to the link and is not seen as a credible threat.
Deployments should limit hubs and downstream switches to IP connected
devices that could be used to place emergency calls. [L7 LCP] SHOULD
use DIGEST authentication (or better) to identify the LIS.
The LoST server, which is the source of Location to PSAP URI mapping,
and local dialstrings, could be spoofed. Use of DHCP to obtain the
location of the server limits the ability to misdirect the user.
LoST protocol use SHOULD include TLS with server certs to prevent
spoofing.
The PSAP could be spoofed. Client SHOULD use TLS with server certs
to prevent spoofing.
10.2. Threats against the Emergency Service
The largest threats to the Emergency Service are forgery of location
and denial of service attacks on the PSAP and/or ESRP.
To mitigate forgery of location, location object SHOULD be signed.
Since access networks and PSAPs are usually local to each other,
providing a PKI should not be onerous for many residential
deployments. However, enterprises may deploy access networks with
location, which is to be encouraged. PKI covering all enterprises
within a PSAP service area may be much more problematic.
To mitigate denial of service attacks, endpoint SHOULD use TLS (which
implies TCP) in the signaling towards the LoST server and the PSAP/
ESRP. Return routability of signaling would help significantly. Use
of P-Asserted-Identity or SIP Identity is also REQUIRED of calling
networks.
11. Normative References
[I-D.ietf-ecrit-framework]
Rosen, B., "Framework for Emergency Calling in Internet
Multimedia", draft-ietf-ecrit-framework-00 (work in
progress), October 2006.
[I-D.ietf-ecrit-lost] [I-D.ietf-ecrit-lost]
Hardie, T., "LoST: A Location-to-Service Translation Hardie, T., "LoST: A Location-to-Service Translation
Protocol", draft-ietf-ecrit-lost-01 (work in progress), Protocol", draft-ietf-ecrit-lost-04 (work in progress),
September 2006. February 2007.
[I-D.ietf-ecrit-service-urn]
Schulzrinne, H., "A Uniform Resource Name (URN) for
Services", draft-ietf-ecrit-service-urn-05 (work in
progress), August 2006.
[I-D.ietf-geopriv-pdif-lo-profile] [I-D.ietf-geopriv-pdif-lo-profile]
Tschofenig, H., "GEOPRIV PIDF-LO Usage Clarification, Tschofenig, H., "GEOPRIV PIDF-LO Usage Clarification,
Considerations and Recommendations", Considerations and Recommendations",
draft-ietf-geopriv-pdif-lo-profile-04 (work in progress), draft-ietf-geopriv-pdif-lo-profile-05 (work in progress),
May 2006. October 2006.
[I-D.ietf-mmusic-media-loopback] [I-D.ietf-mmusic-media-loopback]
Hedayat, K., "An Extension to the Session Description Hedayat, K., "An Extension to the Session Description
Protocol (SDP) for Media Loopback", Protocol (SDP) for Media Loopback",
draft-ietf-mmusic-media-loopback-05 (work in progress), draft-ietf-mmusic-media-loopback-05 (work in progress),
September 2006. September 2006.
[I-D.ietf-sip-gruu] [I-D.ietf-sip-gruu]
Rosenberg, J., "Obtaining and Using Globally Routable User Rosenberg, J., "Obtaining and Using Globally Routable User
Agent (UA) URIs (GRUU) in the Session Initiation Protocol Agent (UA) URIs (GRUU) in the Session Initiation Protocol
(SIP)", draft-ietf-sip-gruu-10 (work in progress), (SIP)", draft-ietf-sip-gruu-11 (work in progress),
August 2006. October 2006.
[I-D.ietf-sip-location-conveyance] [I-D.ietf-sip-location-conveyance]
Polk, J. and B. Rosen, "Session Initiation Protocol Polk, J. and B. Rosen, "Session Initiation Protocol
Location Conveyance", Location Conveyance",
draft-ietf-sip-location-conveyance-04 (work in progress), draft-ietf-sip-location-conveyance-07 (work in progress),
August 2006. February 2007.
[I-D.ietf-sipping-service-examples]
Johnston, A., "Session Initiation Protocol Service
Examples", draft-ietf-sipping-service-examples-12 (work in
progress), January 2007.
[I-D.ietf-sipping-toip] [I-D.ietf-sipping-toip]
Wijk, A. and G. Gybels, "Framework for real-time text over Wijk, A. and G. Gybels, "Framework for real-time text over
IP using the Session Initiation Protocol (SIP)", IP using the Session Initiation Protocol (SIP)",
draft-ietf-sipping-toip-07 (work in progress), draft-ietf-sipping-toip-07 (work in progress),
August 2006. August 2006.
[I-D.rosen-iptel-dialstring] [I-D.rosen-iptel-dialstring]
Rosen, B., "Dialstring parameter for the Session Rosen, B., "Dialstring parameter for the Session
Initiation Protocol Uniform Resource Identifier", Initiation Protocol Uniform Resource Identifier",
draft-rosen-iptel-dialstring-04 (work in progress), draft-rosen-iptel-dialstring-05 (work in progress),
June 2006. March 2007.
[I-D.schulzrinne-geopriv-dhcp-civil]
Schulzrinne, H., "DHCP Option for Civil Location",
draft-schulzrinne-geopriv-dhcp-civil-01 (work in
progress), February 2003.
[I-D.schulzrinne-sipping-service]
Schulzrinne, H., "A Uniform Resource Name (URN) for
Services", draft-schulzrinne-sipping-service-01 (work in
progress), October 2005.
[LLDP] "IEEE802.1ab Station and Media Access Control", Dec 2004. [LLDP] IEEE, "IEEE 802.1AB-2005, Station and Media Access Control
Connectivity Discovery (aka Link Layer Discovery Protocol
- LLDP)", May 2004.
[LLDP-MED] [LLDP-MED]
TIA, "ANSI/TIA-1057 Link Layer Discovery Protocol - Media TIA, "ANSI/TIA-1057, Link Layer Discovery Protocol for
Endpoint Discovery". Media Endpoint Devices (aka LLDP-MED)", Apr 2006.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998. August 1998.
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", [RFC3046] Patrick, M., "DHCP Relay Agent Information Option",
RFC 3046, January 2001. RFC 3046, January 2001.
[RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP
Messages", RFC 3118, June 2001.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002. June 2002.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
June 2002.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325, Asserted Identity within Trusted Networks", RFC 3325,
November 2002. November 2002.
[RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
and D. Gurle, "Session Initiation Protocol (SIP) Extension
for Instant Messaging", RFC 3428, December 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
July 2003.
[RFC3825] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host [RFC3825] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
Configuration Protocol Option for Coordinate-based Configuration Protocol Option for Coordinate-based
Location Configuration Information", RFC 3825, July 2004. Location Configuration Information", RFC 3825, July 2004.
[RFC3856] Rosenberg, J., "A Presence Event Package for the Session
Initiation Protocol (SIP)", RFC 3856, August 2004.
[RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 3920, October 2004.
[RFC3984] Wenger, S., Hannuksela, M., Stockhammer, T., Westerlund,
M., and D. Singer, "RTP Payload Format for H.264 Video",
RFC 3984, February 2005.
[RFC4103] Hellstrom, G. and P. Jones, "RTP Payload for Text [RFC4103] Hellstrom, G. and P. Jones, "RTP Payload for Text
Conversation", RFC 4103, June 2005. Conversation", RFC 4103, June 2005.
[RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object [RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005. Format", RFC 4119, December 2005.
[RFC4190] Carlberg, K., Brown, I., and C. Beard, "Framework for [RFC4190] Carlberg, K., Brown, I., and C. Beard, "Framework for
Supporting Emergency Telecommunications Service (ETS) in Supporting Emergency Telecommunications Service (ETS) in
IP Telephony", RFC 4190, November 2005. IP Telephony", RFC 4190, November 2005.
[RFC4474] Peterson, J. and C. Jennings, "Enhancements for [RFC4474] Peterson, J. and C. Jennings, "Enhancements for
Authenticated Identity Management in the Session Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 4474, August 2006. Initiation Protocol (SIP)", RFC 4474, August 2006.
[RFC4504] Sinnreich, H., Lass, S., and C. Stredicke, "SIP Telephony [RFC4504] Sinnreich, H., Lass, S., and C. Stredicke, "SIP Telephony
Device Requirements and Configuration", RFC 4504, Device Requirements and Configuration", RFC 4504,
May 2006. May 2006.
[framework] [RFC4676] Schulzrinne, H., "Dynamic Host Configuration Protocol
Rosen, B., Polk, J., Schulzrinne, H., and A. Newton, (DHCPv4 and DHCPv6) Option for Civic Addresses
"Framework for Emergency Calling in Internet Multimedia", Configuration Information", RFC 4676, October 2006.
October 2006.
Authors' Addresses Authors' Addresses
Brian Rosen Brian Rosen
NeuStar NeuStar
470 Conrad Dr. 470 Conrad Dr.
Mars, PA 16046 Mars, PA 16046
US US
Phone: +1 724 382 1051 Phone: +1 724 382 1051
skipping to change at page 16, line 7 skipping to change at page 21, line 7
Cisco Systems Cisco Systems
3913 Treemont Circle 3913 Treemont Circle
Colleyville, TX 76034 Colleyville, TX 76034
US US
Phone: +1-817-271-3552 Phone: +1-817-271-3552
Email: jmpolk@cisco.com Email: jmpolk@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
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The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
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