One document matched: draft-olson-sipping-dialog-package-extensions-00.txt
SIPPING S. Olson
Internet-Draft Microsoft
Expires: December 21, 2003 June 22, 2003
Extensions to the Dialog event package for Third Party Call Control
draft-olson-sipping-dialog-package-extensions-00
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
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The list of current Internet-Drafts can be accessed at http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 21, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document defines extensions to the dialog event package and
corresponding application/dialog-info+xml MIME type for the purpose
of third-party call control.
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. A Filter for the dialog event package . . . . . . . . . . . . 6
4.1 XML schema for the filter . . . . . . . . . . . . . . . . . . 6
4.2 Example filters . . . . . . . . . . . . . . . . . . . . . . . 8
5. Extending application/dialog-info+xml . . . . . . . . . . . . 10
5.1 The replaces element . . . . . . . . . . . . . . . . . . . . . 10
5.2 The referred-by element . . . . . . . . . . . . . . . . . . . 11
5.3 The local-target element . . . . . . . . . . . . . . . . . . . 12
5.4 The local-media-state and remote-media-state elements . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
6.1 application/dialog-filter-qbe+xml MIME Registration . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . 18
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1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1].
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2. Introduction
The dialog event package [4] defines a mechanism for monitoring the
progress of INVITE dialogs involving a specific user through a
subscription to that dialog state. The package allows for monitoring
all dialogs for that user or a specific dialog identified by Call-ID
and local and remote tags. Currently undefined is a mechanism for
finer grained filtering of the dialogs for which state is provided.
The state of a dialog is conveyed with respect to a finite state
machine (FSM) defined in the Internet-Draft. This FSM reflects the
transition from the initial INVITE, to a 100 Trying response, to a
1xx response, through a final response (2xx). The application/
dialog-info+xml MIME type defines additional attributes that augment
this FSM state. Still, there is important information not immediately
conveyed by the dialog event package. This missing information
represents additional context for a dialog which helps the watcher
determine which dialogs are interesting and which are not from the
perspective of call control and advanced services [5].
It is the intention of this document to address these issues by:
o defining an XML based MIME type for filtering notifications for
the dialog event
o extending application/dialog-info+xml with new attributes and
elements to provide additional context information
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3. Use Cases
The use cases of interest include the following:
1. The dialog event watcher wishes to be informed of all dialog
state related to dialogs which match a given remote URI
2. The dialog event watcher wishes to know which dialogs are part of
a larger conference
3. The dialog event watcher wishes to know when a dialog goes "on
hold". "On hold" refers to the situation where the two parties of
the dialog are not actively engaged in communication. This
information is valuable feeback for the UA which is responsible
for placing the dialog "on hold". It is also an indication that
the "on hold" party may be available for communication.
4. The dialog event watcher wishes to know which dialogs are part of
a call transfer operation
5. The dialog event watcher wishes to know the relationship between
a new dialog and the dialog which it is replacing
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4. A Filter for the dialog event package
This memo defines a new MIME type (application/dialog-filter-qbe+xml)
which is intended to be placed in the body of a SUBSCRIBE request for
the dialog event package to serve as filter criteria for limiting the
list of dialogs which are returned in subsequent NOTIFYs. It is
expected that SIP devices which support this event package will also
support more advanced conferencing and media services. Therefore, it
will not be unusual for a given device to be a participant in many
simultaneous INVITE dialogs of various types. This is the rationale
behind providing a filtering ability at the subscription target
rather than doing filtering at the watcher. One goal of this
filtering is to reduce network traffic associated with these NOTIFYs.
Another goal is to simplify the implementation of advanced services
by allowing watchers to focus on a narrow subset of the dialogs
associated with a user.
The filter is specified in a query-by-example format. The subscriber
specifies the remote URI, Call-ID, state, tags, etc. of interest and
omits any element which it does not need to match explicitly (a
"don't care" condition). Any element or attribute included in the
filter which is not understood by the receiving UA MUST be ignored.
The filter is composed of a sequence of one or more <dialog>
elements. Each <dialog> element in the filter represents one filter
criteria. The entire filter is the logical "or" of all of these
criteria. Negation is not supported.
The filter can be present in any SUBSCRIBE or re-SUBSCRIBE during the
life of the subscription. The current filter is replaced (not
ammended) by filters in subsequent SUBSCRIBE requests. A subsequent
SUBSCRIBE lacking any filter removes the currently active filter. The
filter is not persisted across subscriptions and is specific to the
subscription dialog. Multiple subscriptions between two UAs may have
independent filters. This memo does not define any mechanism for
querying the currently active filter. Consequently, no versioning
scheme is defined for these filters.
A UA receiving a filter format which it does not understand or honor
MUST return a 415 error response.
4.1 XML schema for the filter
XML Schema for application/dialog-filter-qbe+xml
<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:ietf:params:xml:ns:dialog-filter-qbe"
xmlns:tns="urn:ietf:params:xml:ns:dialog-filter-qbe" elementFormDefault="qualified"
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attributeFormDefault="unqualified">
<!-- This import brings in the XML language attribute xml:lang-->
<xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/03/xml.xsd" />
<xs:element name="dialog-filter">
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:dialog" minOccurs="1" maxOccurs="unbounded" />
<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
<xs:attribute name="entity" type="xs:anyURI" use="optional" />
</xs:complexType>
</xs:element>
<xs:element name="dialog">
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:state" minOccurs="1" maxOccurs="1" />
<xs:element name="duration" type="xs:nonNegativeInteger" minOccurs="0" maxOccurs="1" />
<xs:element name="local-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
<xs:attribute name="id" type="xs:string" use="optional" />
<xs:attribute name="call-id" type="xs:string" use="optional" />
<xs:attribute name="local-tag" type="xs:string" use="optional" />
<xs:attribute name="remote-tag" type="xs:string" use="optional" />
<xs:attribute name="direction" use="optional">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="initiator" />
<xs:enumeration value="recipient" />
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:complexType>
</xs:element>
<xs:element name="state">
<xs:complexType>
<xs:simpleContent>
<xs:restriction base="xs:string">
<xs:enumeration value="trying" />
<xs:enumeration value="proceeding" />
<xs:enumeration value="early" />
<xs:enumeration value="confirmed" />
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<xs:enumeration value="terminated" />
<xs:attribute name="event" use="optional">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="1xx-notag" />
<xs:enumeration value="1xx-tag" />
<xs:enumeration value="2xx" />
<xs:enumeration value="cancelled" />
<xs:enumeration value="rejected" />
<xs:enumeration value="hungup" />
<xs:enumeration value="error" />
<xs:enumeration value="timeout" />
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="code" use="optional">
<xs:simpleType>
<xs:restriction base="xs:nonNegativeInteger">
<xs:maxInclusive value="699" />
<xs:minInclusive value="100" />
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:restriction>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:complexType name="nameaddr">
<xs:simpleContent>
<xs:extension base="xs:anyURI">
<xs:attribute name="display-name" type="xs:string" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:schema>
4.2 Example filters
Example 1: Filtering for all dialogs with a specified URI
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-filter xmlns="urn:ietf:params:xml:ns:dialog-filter-qbe">
<dialog>
<remote-uri>sip:helpdesk@tradewind.com</remote-uri>
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</dialog>
</dialog-filter>
Example 2: Filtering for all inbound dialogs
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-filter xmlns="urn:ietf:params:xml:ns:dialog-filter-qbe">
<dialog direction="recipient" />
</dialog-filter>
Example 3: Filtering for dialogs that share a given Call-ID or which
are to a given URI
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-filter xmlns="urn:ietf:params:xml:ns:dialog-filter-qbe">
<dialog>
<remote-uri>sip:conf-factory@tradewind.com</remote-uri>
</dialog>
<dialog call-id="3@conf-factory.tradewind.com" />
</dialog-filter>
Example 4: Filtering for all dialogs in the trying, proceeding, or
early states
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-filter xmlns="urn:ietf:params:xml:ns:dialog-filter-qbe">
<dialog><state>trying</state></dialog>
<dialog><state>early</state></dialog>
<dialog><state>proceeding</state></dialog>
</dialog-filter>
Example 5: Filtering for a specific dialog
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-filter xmlns="urn:ietf:params:xml:ns:dialog-filter-qbe">
<dialog call-id="5@conf-factory.tradewind.com" local-tag="456456" remote-tag="23490923" />
</dialog-filter>
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5. Extending application/dialog-info+xml
There are three extensions proposed to the XML schema for the
application/dialog-info+xml MIME type:
An extension to indicate that a dialog is being established to
replace another existing dialog
An extension to indicate that a dialog is being established as a
result of a refer request
An extension to indicate the local Contact information for a
dialog analogous to "remote-target"
All of these extensions are intended to make it easier to correlate
dialog information with actions such as blind and consultative
transfer as well as multiparty conferencing.
5.1 The replaces element
The <replaces> element is a proposed new child of the <dialog>
element. The purpose is to capture the information of the Replaces
headers [6] including the Call-ID, local tag, and remote tag of the
dialog which this new dialog is intended to replace.
Example of <replaces> element in dialog-info
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info" state="full" version="3" entity="a@tradewind.com">
<dialog id="1" call-id="7777@b.tradewind.com" local-tag="456456" remote-tag="234903">
<state>confirmed</state>
</dialog>
<dialog id="2" call-id="4555@c.tradewind.com" local-tag="234231" remote-tag="982321">
<state>proceeding</state>
<replaces call-id="7777@b.tradewind.com" local-tag="456456" remote-tag="234903" />
</dialog>
</dialog-info>
Schema for <replaces> element in dialog-info
<xs:element name="dialog">
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:state" minOccurs="1" maxOccurs="1" />
<xs:element name="duration" type="xs:nonNegativeInteger" minOccurs="0" maxOccurs="1" />
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<xs:element name="local-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element ref="tns:replaces" minOccurs="0" maxOccurs="1" />
<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="replaces">
<xs:complexType>
<xs:simpleContent />
</xs:complexType>
<xs:attribute name="call-id" type="xs:string" use="optional" />
<xs:attribute name="local-tag" type="xs:string" use="optional" />
<xs:attribute name="remote-tag" type="xs:string" use="optional" />
</xs:element>
5.2 The referred-by element
The <referred-by> element is a proposed new child of the <dialog>
element containing the name-addr of the source of the REFER which
caused the creation of that dialog. The purpose of this element is to
signal that a dialog was created as part of a call transfer and to
identify the source of that transfer operation. The referred-by
element SHOULD be included whenever an INVITE dialog is established
in response to a REFER request.
Example of <referred-by> element in dialog-info
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info" state="partial" version="3" entity="a@tradewind.com">
<dialog id="4" call-id="4555@c.tradewind.com" local-tag="234231" remote-tag="982321">
<state>early</state>
<referred-by display-name="Help Desk">helpdesk@tradewind.com</referred-by>
</dialog>
</dialog-info>
Schema for <referred-by> element in dialog-info
<xs:element name="dialog">
<xs:complexType>
<xs:sequence>
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<xs:element ref="tns:state" minOccurs="1" maxOccurs="1" />
<xs:element name="duration" type="xs:nonNegativeInteger" minOccurs="0" maxOccurs="1" />
<xs:element name="local-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element ref="tns:replaces" minOccurs="0" maxOccurs="1" />
<xs:element name="referred-by" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
5.3 The local-target element
The <local-target> element is a proposed child element of the
<dialog> element. Its purpose and construction are similar to the
remote-target element defined today. The local-target is intended to
carry the local-target URI for this UA for this dialog as defined by
SIP [2]. The local-target should be present whenever the
remote-target element is present. The local-target (and
remote-target) should be updated whenever a target refresh operation
occurs for this dialog. The primary goal of conveying this
information is to capture uniquely identifying information for
dialogs which are part of a larger conference (such as the conference
URI).
Example of <local-target> element in dialog-info
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info" state="partial" version="3" entity="a@tradewind.com">
<dialog id="4" call-id="4555@c.tradewind.com" local-tag="234231" remote-tag="982321">
<state>early</state>
<local-target>sip:conf-2342342@conf-factory.tradewind.com</local-target>
<remote-target>sip:conf-leader@b.tradewind.com</remote-target>
</dialog>
</dialog-info>
Schema for <local-target> element in dialog-info
<xs:element name="dialog">
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:state" minOccurs="1" maxOccurs="1" />
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<xs:element name="duration" type="xs:nonNegativeInteger" minOccurs="0" maxOccurs="1" />
<xs:element name="local-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="local-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element ref="tns:replaces" minOccurs="0" maxOccurs="1" />
<xs:element name="referred-by" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
5.4 The local-media-state and remote-media-state elements
The <local/remote-media-state> elements are proposed children of the
<dialog> element. Their purpose is to convey the current
directionality of media and consequently the level of participation
of each party in the dialog. This information corresponds to the
"sendonly", "sendrecv", "recvonly", and "inactive" attributes of SDP
[7] and their usage as defined in RFC 3264 [3]. The default value for
these elements in their absence is "sendrecv". Note that for
backwards compatibility, a SDP connection address of "0.0.0.0" is to
be interpreted and relayed as a media-state of "inactive".
Example of <local/remote-media-state> element in dialog-info
<?xml version="1.0" encoding="UTF-8" ?>
<dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info" state="partial" version="3" entity="a@tradewind.com">
<dialog id="4" call-id="4555@c.tradewind.com" local-tag="234231" remote-tag="982321">
<state>confirmed</state>
<local-media-state>sendonly</local-media-state>
<remote-media-state>inactive</remote-media-state>
</dialog>
</dialog-info>
Schema for <local/remote-media-state> element in dialog-info
<xs:element name="dialog">
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:state" minOccurs="1" maxOccurs="1" />
<xs:element name="duration" type="xs:nonNegativeInteger" minOccurs="0" maxOccurs="1" />
<xs:element name="local-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
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<xs:element name="remote-uri" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="local-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-target" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:element name="local-media-state" type="tns:media-state" minOccurs="0" maxOccurs="1" />
<xs:element name="remote-media-state" type="tns:media-state" minOccurs="0" maxOccurs="1" />
<xs:element ref="tns:replaces" minOccurs="0" maxOccurs="1" />
<xs:element name="referred-by" type="tns:nameaddr" minOccurs="0" maxOccurs="1" />
<xs:any namespace="##other" processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:simpleType name="media-state">
<xs:restriction base="xs:string">
<xs:enumeration value="sendrecv" />
<xs:enumeration value="recvonly" />
<xs:enumeration value="sendonly" />
<xs:enumeration value="inactive" />
</xs:restriction>
</xs:simpleType>
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6. IANA Considerations
6.1 application/dialog-filter-qbe+xml MIME Registration
MIME media type name: application
MIME subtype name: dialog-filter-qbe+xml
Mandatory parameters: none
Optional parameters: Same as charset parameter for application/xml as
specified in RFC 3023 [8]
Encoding considerations: Same as encoding considerations for
application/xml as specified in RFC 3023 [8]
Security considerations: See section 10 of RFC 3023 [8]
Interoperability considerations: none
Published specification: this document
Applications which use this media type: Conference calling and
advanced services built using SIP
Additional Information:
Magic Number: none
File extension: .xml
Macintosh file type code: "TEXT"
Personal and email address for further information: Sean Olson
<seanol@microsoft.com>
Intended usage: COMMON
Author/Change controller: The IETF.
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7. Security Considerations
The <referred-by> element is subject to the same security
implications as a Referred-By header in a REFER request. Further
investigation is necessary to determine how best to address this
security concern. Namely, should the referred-by element contain
an AIB or perhaps use xmlsig to integrity protect the information?
Or should the entire dialog-info XML document be secured using S/
MIME when a referred-by element is present?
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References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[3] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002.
[4] Rosenberg, J. and H. Schulzrinne, "An INVITE Inititiated Dialog
Event Package for the Session Initiation Protocol (SIP",
draft-ietf-sipping-dialog-package-01 (work in progress), March
2003.
[5] Johnston, A. and O. Levin, "Session Initiation Protocol Call
Control - Conferencing for User Agents",
draft-ietf-sipping-cc-conferencing-00 (work in progress), April
2003.
[6] Dean, R., Biggs, B. and R. Mahy, "The Session Inititation
Protocol (SIP) 'Replaces' Header", draft-ietf-sip-replaces-03
(work in progress), March 2003.
[7] Handley, M. and V. Jacobson, "SDP: Session Description
Protocol", RFC 2327, April 1998.
[8] Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC
3023, January 2001.
Author's Address
Sean Olson
Microsoft
One Microsoft Way
Redmond, WA 98052
US
Phone: +1-425-707-2846
EMail: seanol@microsoft.com
URI: http://www.microsoft.com/rtc
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Intellectual Property Statement
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intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
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Internet-Draft Extensions to the Dialog event package for Third Party Call Control June 2003
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Olson Expires December 21, 2003 [Page 19]
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