rfc8787xml2.original.xml   rfc8787.xml 
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<rfc category="std" ipr="trust200902" updates="6442" docName="draft-ietf-sipcore
-locparam-06">
<?rfc strict="yes" ?>
<?rfc toc="yes"?>
<?rfc tocdepth="4"?>
<?rfc symrefs="yes"?>
<?rfc iprnotified="no" ?>
<?rfc sortrefs="yes" ?>
<?rfc compact="yes" ?>
<?rfc subcompact="no" ?>
<front> <!DOCTYPE rfc SYSTEM "rfc2629-xhtml.ent">
<title abbrev="Location Parameter">Location Source Parameter for the SIP Geo
location Header Field</title>
<author initials="J." surname="Winterbottom" fullname="James Winterbottom">
<organization>Winterb Consulting Services</organization>
<address>
<postal>
<street/>
<city>Gwynneville</city>
<region>NSW</region>
<code>2500</code>
<country>AU</country>
</postal>
<phone>+61 448 266004</phone>
<email>a.james.winterbottom@gmail.com</email>
</address>
</author>
<author initials="R." surname="Jesske" fullname="Roland Jesske">
<organization>Deutsche Telekom</organization>
<address>
<postal>
<street>Heinrich-Hertz Str, 3-7</street>
<city>Darmstadt</city>
<code>64295</code>
<country>Germany</country>
</postal>
<phone></phone>
<email>r.jesske@telekom.de</email>
<uri>www.telekom.de</uri>
</address>
</author>
<author initials="B." surname="Chatras" fullname="Bruno Chatras">
<organization>Orange Labs</organization>
<address>
<postal>
<street>44, avenue de la République</street>
<city>Châtillon </city>
<code>F-92320</code>
<country>France</country>
</postal>
<phone></phone>
<email>bruno.chatras@orange.com</email>
</address>
</author>
<author fullname="Andrew Hutton" initials="A." surname="Hutto <rfc xmlns:xi="http://www.w3.org/2001/XInclude" submissionType="IETF"
n"> category="std" consensus="true" ipr="trust200902" updates="6442"
<organization>Atos</organization> docName="draft-ietf-sipcore-locparam-06" number="8787" obsoletes=""
<address> xml:lang="en" tocInclude="true" tocDepth="4" symRefs="true"
<postal> sortRefs="true" version="3">
<street>Mid City Place</street>
<city>London</city>
<code>WC1V 6EA</code>
<country>UK</country>
</postal>
<phone></phone>
<email>andrew.hutton@atos.net</email>
</address>
</author>
<date year="2020"/> <front>
<area>ART</area> <title abbrev="Location Parameter">Location Source Parameter for the SIP
<workgroup>SIPCORE</workgroup> Geolocation Header Field</title>
<keyword>Internet-Draft</keyword> <seriesInfo name="RFC" value="8787"/>
<keyword>Emergency</keyword> <author initials="J." surname="Winterbottom" fullname="James Winterbottom">
<keyword>Call</keyword> <organization>Winterb Consulting Services</organization>
<keyword>Location</keyword> <address>
<postal>
<street/>
<city>Gwynneville</city>
<region>NSW</region>
<code>2500</code>
<country>Australia</country>
</postal>
<phone>+61 448 266004</phone>
<email>a.james.winterbottom@gmail.com</email>
</address>
</author>
<author initials="R." surname="Jesske" fullname="Roland Jesske">
<organization>Deutsche Telekom</organization>
<address>
<postal>
<street>Heinrich-Hertz Str, 3-7</street>
<city>Darmstadt</city>
<code>64295</code>
<country>Germany</country>
</postal>
<phone/>
<email>r.jesske@telekom.de</email>
<uri>www.telekom.de</uri>
</address>
</author>
<author initials="B." surname="Chatras" fullname="Bruno Chatras">
<organization>Orange Labs</organization>
<address>
<postal>
<street>44, avenue de la Republique</street>
<city>Chatillon </city>
<code>F-92320</code>
<country>France</country>
</postal>
<phone/>
<email>bruno.chatras@orange.com</email>
</address>
</author>
<author fullname="Andrew Hutton" initials="A." surname="Hutton">
<organization>Atos</organization>
<address>
<postal>
<street>Mid City Place</street>
<city>London</city>
<code>WC1V 6EA</code>
<country>United Kingdom</country>
</postal>
<phone/>
<email>andrew.hutton@atos.net</email>
</address>
</author>
<date year="2020" month="May"/>
<area>ART</area>
<workgroup>SIPCORE</workgroup>
<keyword>Emergency</keyword>
<keyword>Call</keyword>
<keyword>Location</keyword>
<abstract>
<t>There are some circumstances where a Geolocation header field may
contain more than one locationValue. Knowing the identity of the node
adding the locationValue allows the recipient more freedom in selecting
the value to look at first rather than relying solely on the order of
the locationValues. This document defines the "loc-src" parameter so
that the entity adding the locationValue to the Geolocation header
field can identify itself using its hostname. This document updates
RFC 6442.
</t>
</abstract>
</front>
<middle>
<abstract> <section anchor="intro" numbered="true" toc="default">
<t>There are some circumstances where a Geolocation header field may conta <name>Introduction</name>
in more than
one locationValue. Knowing the identity of the node adding the locationVal
ue allows
the recipient more freedom in selecting the value to look at first rather
than relying
solely on the order of the locationValues.
This document defines the "loc-src" parameter so that the entity adding th
e locationValue to
Geolocation header field can identify itself using its hostname.
This document updates RFC 6442.
</t>
</abstract> <t>
</front> The SIP Geolocation specification <xref target="RFC6442"
<middle> format="default"/> describes the "Geolocation" SIP header field,
<!-- *************************************************************************** which is used to indicate that the SIP message is conveying location
************************** --> information. <xref target="RFC6442" format="default"/> specifies
that SIP intermediaries should not add locationValues to a SIP
request that already contains a locationValue. <xref target="RFC6442"
format="default"/> also states that if a SIP intermediary adds
location, it is fully responsible for addressing the concerns of any
424 (Bad Location Information) SIP response it receives.
<section anchor="intro" title="Introduction"> However, some communications architectures, such as 3GPP <xref
<t> target="TS23-167" format="default"/> and ETSI <xref target="M493"
The SIP Geolocation specification <xref target="RFC6442"/> describes format="default"/>, prefer to use information provided by edge
the "Geolocation" SIP header field which is used to indicate that the S proxies or acquired through the use of core-network nodes before
IP message is conveying location using information provided solely by user equipment (UE). These
information. <xref target="RFC6442"/> specifies that SIP intermediaries solutions don't preclude the use of UE-provided location but require
should not add locationValues to a SIP request that already contains locationVa a means of being able to distinguish the identity of the node adding
lue. the locationValue to the SIP message from that provided by the UE.
<xref target="RFC6442"/> also states that if a SIP intermediary adds location it </t>
is fully responsible for addressing the concerns of any <t>
424 (Bad Location Information) SIP response it receives. <xref target="RFC6442" format="default"/> stipulates that the order
of locationValues in the Geolocation header field is the same as the
order in which they were added to the header field. Whilst this
order provides guidance to the recipient as to which values were
added to the message earlier in the communication chain, it does not
identify which node added the locationValue. Knowing the identity of
the entity that added the location to the message allows the
recipient to choose which location to consider first rather than
relying solely on the order of the locationValues in the Geolocation
header field.
However, some communications architectures, such as 3GPP </t>
<xref target="TS23-167"/> and ETSI <xref target="M493"/>, prefer to use <t>
information provided by edge proxies or acquired through the use of cor This document extends the Geolocation header field of <xref
e-network target="RFC6442" format="default"/> by allowing an entity adding the
nodes, before using information provided solely by user equipment (UE). locationValue to identify itself using a hostname. This is done by
These defining a new geoloc-param header field parameter, "loc-src". How
solutions don't preclude the use of UE-provided location but require a the entity adding the locationValue to the header field obtains the
means of location information is out of scope of this document. Please note
being able to distinguish the identity of the node adding the locationV that the "loc-src" parameter field does not alter the subject of the
alue to locationValue.
the SIP message from that provided by the UE. </t>
</t> </section>
<t>
<xref target="RFC6442"/> stipulates that the order of locationValues in
the
Geolocation header field is the same as the order in which they were ad
ded to the
header field. Whilst this order provides guidance to the recipient as t
o which
values were added to the message earlier in the communication chain, it
does not
identify which node added the locationValue. Knowing
the identity of the entity that added the location to the message allow
s the
recipient to choose which location to consider first rather than relyin
g solely
on the order of the locationValues in the Geolocation header field.
</t> <section anchor="terminology" numbered="true" toc="default">
<t> <name>Terminology</name>
This document extends the Geolocation header field of <xref target="RFC64
42"/>, by allowing an entity adding the locationValue to identify itself using a
hostname. This is done by defining a new geoloc-param header field parameter, "
loc-src". How the entity
adding the locationValue to the header field obtains the location informa
tion
is out of scope of this document.
Please note that the "loc-src" parameter field does not alter the subject
of the locationValue.
</t>
</section>
<!-- ***********************************************************************
****************************** -->
<section anchor="terminology" title="Terminology"> <t>
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", " The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" i "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
n this document are to be interpreted as described in BCP 14 <xref target="RFC21 NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
19"/> <xref target="RFC8174"/> when, and only when, they appear in all capitals, "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
as shown here. "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are
to be interpreted as described in BCP&nbsp;14 <xref target="RFC2119"/>
<xref target="RFC8174"/> when, and only when, they appear in all capitals,
as shown here.
</t> </t>
</section>
<!-- *************************************************************************** </section>
************************** -->
<?rfc needLines="30" ?>
<section anchor="rationale" title="Rationale">
<section anchor="rationale" numbered="true" toc="default">
<name>Rationale</name>
<t>The primary intent of the "loc-src" parameter in this specification is for use in <t>The primary intent of the "loc-src" parameter in this specification is for use in
emergency calling. There are various architectures defined for providin g emergency calling. There are various architectures defined for providin g
emergency calling using SIP-based messaging. Each has its own character istics emergency calling using SIP-based messaging. Each has its own character istics
with corresponding pros and cons. All of them allow the UE to provide l ocation with corresponding pros and cons. All of them allow the UE to provide l ocation
information; however, many also attach other sources of location inform ation to information; however, many also attach other sources of location inform ation to
support veracity checks, provide backup information, or to be used as t he primary support veracity checks, to provide backup information, or to be used a s the primary
location. location.
</t>
<t> This document does not comment on these various architectures or on
the rationale for including multiple
locationValues. It does
recognize that these architectures exist and that there is a need to id
entify
the entity adding the location information.
</t> </t>
<t>The "loc-src" parameter adds the location source generating the locatio <t> This document does not comment on these various architectures or on
nValue the rationale for including multiple locationValues. It does recognize
to allow recipients to make informed decisions about which of multiple that these architectures exist and that there is a need to identify the
values to use. entity adding the location information.
</t> </t>
<t> The "loc-src" parameter is applicable within a single
<t>The "loc-src" parameter adds the location source generating the
locationValue to allow recipients to make informed decisions about which
of the multiple values to use.
</t>
<t> The "loc-src" parameter is applicable within a single
private administrative domain or between different administrative private administrative domain or between different administrative
domains where there is a trust relationship between the domains. domains where there is a trust relationship between the domains.
Thus it is intended to use this parameter only in trust domains Thus, it is intended to use this parameter only in trust domains
where Spec(T) as described in <xref target="RFC3325"/> exists. where Spec(T) as described in <xref target="RFC3325" format="default"/>
</t> exists.
<t>The "loc-src" parameter is not included in a SIP message </t>
<t>The "loc-src" parameter is not included in a SIP message
sent to another network if there is no trust relationship. sent to another network if there is no trust relationship.
The "loc-src" parameter is not applicable if the administrative domain manages The "loc-src" parameter is not applicable if the administrative domain manages
emergency calls in a way that does not require any generation of the l ocation. emergency calls in a way that does not require any generation of the l ocation.
</t> </t>
<t> <t>
The functional architecture to support emergency caller location describ The functional architecture to support emergency caller location describ
ed within ETSI <xref target="M493"/> is an ed within ETSI <xref target="M493" format="default"/> is an
example of an architecture where it makes sense to use this example of an architecture where it makes sense to use this
parameter. parameter.
</t> </t>
</section>
</section> <section anchor="mechanism" numbered="true" toc="default">
<name>Mechanism</name>
<section anchor="mechanism" title="Mechanism">
<t> <t>
The mechanism adds a geoloc-param parameter to the locationValue The mechanism adds a geoloc-param parameter to the locationValue
defined in <xref target="RFC6442"/> that identifies the hostname of the enti ty defined in <xref target="RFC6442" format="default"/> that identifies the hos tname of the entity
adding the locationValue to the Geolocation header field. adding the locationValue to the Geolocation header field.
The Augmented BNF (ABNF) <xref target="RFC5234"/> for this parameter is The Augmented BNF (ABNF) <xref target="RFC5234"
shown in <xref target="ABNF"/>. format="default"/> for this parameter is shown in <xref target="ABNF"
format="default"/>.
</t> </t>
<figure anchor="ABNF" title="Location Source"><artwork><![CDATA[ <figure anchor="ABNF">
<name>Location Source</name>
location-source = “loc-src” EQUAL hostname <sourcecode type="abnf"><![CDATA[
hostname = <defined in RFC3261> location-source = "loc-src" EQUAL hostname
hostname = <defined in RFC 3261>
]]></artwork></figure> ]]></sourcecode>
<t> Only a fully qualified host name is valid. The syntax does
not support IP addresses, and if an entity conforming to this
specification receives a Geolocation header field with a "loc-src" parameter
containing an IP address, it MUST remove the parameter.</t>
<t>A SIP intermediary conformant to this specification adding a l
ocationValue to a Geolocation header field SHOULD also add a "loc-src" header fi
eld parameter so that it is clearly
identified as the node adding the location. A User Agent (UA)
MUST NOT insert a "loc-src" header field parameter. If a SIP intermediary receiv
es a message from an untrusted source with
the "loc-src" parameter set then it MUST remove the "loc-src"
parameter before
passing the message into a trusted network.
</t>
</figure>
<t> Only a fully qualified host name is valid. The syntax does not
support IP addresses, and if an entity conforming to this specification
receives a Geolocation header field with a "loc-src" parameter
containing an IP address, it <bcp14>MUST</bcp14> remove the
parameter.</t>
<t>A SIP intermediary conformant to this specification adding a
locationValue to a Geolocation header field <bcp14>SHOULD</bcp14> also
add a "loc-src" header field parameter so that it is clearly identified
as the node adding the location. A User Agent (UA) <bcp14>MUST
NOT</bcp14> insert a "loc-src" header field parameter. If a SIP
intermediary receives a message from an untrusted source with the
"loc-src" parameter set, then it <bcp14>MUST</bcp14> remove the "loc-src"
parameter before passing the message into a trusted network.
</t>
</section> </section>
<!-- *************************************************************************** ************************** -->
<!-- ******************************************************************** <section anchor="example" numbered="true" toc="default">
********************************* --> <name>Example</name>
<section anchor="example" title="Example"> <t>
<t> The following example shows a SIP INVITE message containing a
The following example shows a SIP INVITE message containing a Geo Geolocation header field with two locationValues. The first
location header locationValue points to a Presence Information Data Format
field with two locationValues. The first locationValue points to Location Object (PIDF-LO) in the SIP body using a
a PIDF-LO content-indirection (cid:) URI per <xref target="RFC4483"
in the SIP body using a content-indirection (cid:) URI per <xref format="default"/>, and this is provided by the UE. The second
target="RFC4483"/> locationValue is an https URI provided by a SIP intermediary,
and this is provided by the UE. The second locationValue is an ht which identifies itself using the "loc-src" parameter.
tps URI </t>
provided by a SIP intermediary which identifies itself using the <figure anchor="locationRequest">
"loc-src" parameter. <name>Example Location Request (in Trust Domain)</name>
</t> <sourcecode>
<figure anchor="locationRequest" title="Example Location Request (in trus
t domain)"><artwork><![CDATA[
INVITE sip:bob@biloxi.example.com SIP/2.0 INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bK74bf9 Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bK74bf9
Max-Forwards: 70 Max-Forwards: 70
To: Bob <sip:bob@biloxi.example.com> To: Bob &lt;sip:bob@biloxi.example.com&gt;
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl From: Alice &lt;sip:alice@atlanta.example.com&gt;;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com Call-ID: 3848276298220188511@atlanta.example.com
Geolocation: <cid:target123@atlanta.example.com>, Geolocation: &lt;cid:target123@atlanta.example.com&gt;,
<https://lis.example.com:8222/y77syc7cuecbh>; &lt;https://lis.example.com:8222/y77syc7cuecbh&gt;;
loc-src=edgeproxy.example.com loc-src=edgeproxy.example.com
Geolocation-Routing: yes Geolocation-Routing: yes
Accept: application/sdp, application/pidf+xml Accept: application/sdp, application/pidf+xml
CSeq: 31862 INVITE CSeq: 31862 INVITE
Contact: <sip:alice@atlanta.example.com&gt; Contact: <sip:alice@atlanta.example.com&gt;
Content-Type: multipart/mixed; boundary=boundary1 Content-Type: multipart/mixed; boundary=boundary1
Content-Length: ... Content-Length: ...
]]></artwork></figure> </sourcecode>
</figure>
</section> </section>
<!-- ***************************************************************************
************************** -->
<!-- *************************************************************************
**************************** -->
<section anchor="privacy" title="Privacy Considerations"> <section anchor="privacy" numbered="true" toc="default">
<name>Privacy Considerations</name>
<t>This document doesn't change any of the privacy considerations describe d in <t>This document doesn't change any of the privacy considerations describe d in
<xref target="RFC6442"/>. While the addition of the "loc-src" <xref target="RFC6442" format="default"/>. While the addition of the "l oc-src"
parameter identifies the entity that added the location in the parameter identifies the entity that added the location in the
signaling path, this addition provides little more exposure signaling path, this addition provides little more exposure
than adding a proxy identity to the Record-Route header field (privacy defin ed in <xref target="RFC3323"/>).</t> than adding a proxy identity to the Record-Route header field (privacy defin ed in <xref target="RFC3323" format="default"/>).</t>
</section> </section>
<!-- ************************************************************************ <section anchor="security" numbered="true" toc="default">
***************************** --> <name>Security Considerations</name>
<section anchor="security" title="Security Considerations">
<t>This document introduces the ability of a SIP intermediary to insert <t>This document introduces the ability of a SIP intermediary to insert
a host name indicating that they added the specific locationValue to the a host name indicating that they added the specific locationValue to the
Geolocation header field. The intent is for this field to be used by the location Geolocation header field. The intent is for this field to be used by the location
recipient in the event that the SIP message contains multiple locationVa lues. recipient in the event that the SIP message contains multiple locationVa lues.
As a consequence this parameter should only be used by the location reci As a consequence, this parameter should only be used by the location rec
pient ipient
in a trusted network. Adding this parameter in an untrusted network serv in a trusted network. Adding this parameter in an untrusted network serv
es solely to give location information to untrusted parties, and is NOT RECOMMEN es solely to give location information to untrusted parties and is <bcp14>NOT RE
DED. COMMENDED</bcp14>.
</t> </t>
<t> As already stated in <xref target="RFC6442"/>, securing the location <t> As already stated in <xref target="RFC6442" format="default"/>,
hop-by-hop, using TLS, protects the message from eavesdropping and securing the location hop by hop, using TLS, protects the message from
modification in transit, but exposes the information to all SIP intermediarie eavesdropping and modification in transit but exposes the information
s to all SIP intermediaries on the path as well as the endpoint. The
on the path as well as the endpoint. The "loc-src" parameter is applicable wi "loc-src" parameter is applicable within a single private administrative
thin a single domain or between different administrative domains where there is a
private administrative domain or between different administrative relationship between the domains. If such a trust relationship is not
domains where there is a relationship between the domains. If such trus given, it is strongly recommended to delete the location information.
t relationship is not given, it is strongly recommended to delete the location i </t>
nformation. <t>
</t> The use of this parameter is not restricted to a specific architecture, but
<t> using multiple locations and loc-src may end in compatibility issues. <xref
The use of this parameter is not restricted to a specific architecture but using target="RFC6442" format="default"/> already addresses the issue of multiple
multiple locations and loc-src may locations. To avoid problems of a possible corruption of the location
end in compatibility issues. <xref target="RFC6442"/> already addresses the information including the "loc-src" parameter when using an untrusted
issue of multiple locations. relationship, it is strongly recommended to delete location information when
To avoid problems of a possible corruption of the location information passed to another domain out of the trust domain.
including the "loc-src" parameter when using a untrusted relationship, it is str
ongly recommended to delete location information when passed to another domain o
ut of the trust domain.
</t>
</t>
</section> </section>
<!-- ************************************************************************ <section anchor="iana" numbered="true" toc="default">
***************************** --> <name>IANA Considerations</name>
<section numbered="true" toc="default">
<section anchor="iana" title="IANA Considerations"> <name>Registration of "loc-src" Parameter for Geolocation Header Field</
<section title="Registration of loc-src parameter for Geolocation header f name>
ield"> <t>IANA has added a new SIP header field parameter for
<t> The IANA is asked to add a new SIP header field parameter for
the Geolocation header field in the "Header Field Parameters and the Geolocation header field in the "Header Field Parameters and
Parameter Values" subregistry (created by <xref target="RFC3968"/>) of the Parameter Values" subregistry (created by <xref target="RFC3968" format="def ault"/>) of the
"Session Initiation Protocol (SIP) Parameters" registry found at "Session Initiation Protocol (SIP) Parameters" registry found at
https://www.iana.org/assignments/sip-parameters/. <eref target="https://www.iana.org/assignments/sip-parameters/" brackets="an gle"/>.
<list style="hanging">
<t hangText="Header Field:">Geolocation</t>
<t hangText="Parameter Name:">loc-src</t>
<t hangText="Predefined Values:">No</t>
<t hangText="Reference:">this RFC</t>
</list>
</t> </t>
<dl newline="false" spacing="normal">
<dt>Header Field:</dt>
<dd>Geolocation</dd>
<dt>Parameter Name:</dt>
<dd>loc-src</dd>
<dt>Predefined Values:</dt>
<dd>No</dd>
<dt>Reference:</dt>
<dd>RFC 8787</dd>
</dl>
</section> </section>
</section> </section>
<!-- ************************************************************************
***************************** -->
<section title="Acknowledgements">
<t>The authors would like to thank Dale Worley, Christer Holmberg and Jean
Mahoney for their extensive review of the draft.
The authors would like to acknowledge the constructive feedback provided b
y Paul Kyzivat and Robert Sparks.</t>
</section>
</middle> </middle>
<back> <back>
<references title="Normative References"> <references>
<?rfc include="reference.RFC.2119"?> <name>References</name>
<?rfc include="reference.RFC.6442"?> <references>
<?rfc include="reference.RFC.5234"?> <name>Normative References</name>
<?rfc include="reference.RFC.3325"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.8174"?> FC.2119.xml"/>
<?rfc include="reference.RFC.3968"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.3323"?> FC.6442.xml"/>
</references> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<references title="Informative References"> FC.5234.xml"/>
<?rfc include="reference.RFC.4483"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3325.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3968.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3323.xml"/>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.tools.ietf.org/public/rfc/bibxml/refer
ence.RFC.4483.xml"/>
<reference anchor="TS23-167"> <reference anchor="TS23-167">
<front> <front>
<title>3rd Generation Partnership Project; <title>Technical Specification Group Services and System Aspects; IP
Technical Specification Group Services and System Aspects; Multimedia Subsystem (IMS) emergency sessions
IP Multimedia Subsystem (IMS) emergency sessions </title>
</title>
<author>
<organization abbrev="3GPP">
3rd Generation Partnership Project
</organization>
</author>
<date month="March" year="2015" /> <author>
</front> <organization>3rd Generation Partnership Project
<seriesInfo name="TS" value="23.167" /> </organization>
<seriesInfo name="V" value="12.1.0" /> </author>
</reference> <date month="March" year="2015"/>
<reference anchor="M493"> </front>
<front> <refcontent>TS 23.167</refcontent>
<title>Functional architecture to support European requirements <refcontent>V12.1.0
</refcontent>
</reference>
<reference anchor="M493">
<front>
<title>Functional architecture to support European requirements
on emergency caller location determination and transport</title> on emergency caller location determination and transport</title>
<author> <author>
<organization abbrev="ETSI"> <organization>
European Telecommunications Standards Institute European Telecommunications Standards Institute
</organization> </organization>
</author> </author>
<date month="February" year="2015"/>
<date month="February" year="2015" /> </front>
</front> <refcontent>ES 203 178</refcontent>
<seriesInfo name="ES" value="203 178" /> <refcontent>V 1.1.1
<seriesInfo name="V" value="1.1.1" /> </refcontent>
</reference> </reference>
</references>
</references> </references>
<section numbered="false" toc="default">
<name>Acknowledgements</name>
<t>The authors would like to thank <contact fullname="Dale Worley"/>,
<contact fullname="Christer Holmberg"/>, and <contact fullname="Jean Mahon
ey"/> for their
extensive review of this document. The authors would like to
acknowledge the constructive feedback provided by <contact fullname="Paul
Kyzivat"/> and
<contact fullname="Robert Sparks"/>.</t>
</section>
</back> </back>
</rfc> </rfc>
 End of changes. 48 change blocks. 
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