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.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   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.













Olson                  Expires December 21, 2003                [Page 1]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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
































Olson                  Expires December 21, 2003                [Page 2]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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].














































Olson                  Expires December 21, 2003                [Page 3]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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
























Olson                  Expires December 21, 2003                [Page 4]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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





























Olson                  Expires December 21, 2003                [Page 5]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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"



Olson                  Expires December 21, 2003                [Page 6]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


              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" />



Olson                  Expires December 21, 2003                [Page 7]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


                  <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>



Olson                  Expires December 21, 2003                [Page 8]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


          </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>






Olson                  Expires December 21, 2003                [Page 9]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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" />



Olson                  Expires December 21, 2003               [Page 10]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


               <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>



Olson                  Expires December 21, 2003               [Page 11]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


               <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" />



Olson                  Expires December 21, 2003               [Page 12]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


               <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" />



Olson                  Expires December 21, 2003               [Page 13]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


               <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>































Olson                  Expires December 21, 2003               [Page 14]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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.












Olson                  Expires December 21, 2003               [Page 15]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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?










































Olson                  Expires December 21, 2003               [Page 16]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


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







Olson                  Expires December 21, 2003               [Page 17]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   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
   has made any effort to identify any such rights. Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11. Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard. Please address the information to the IETF Executive
   Director.


Full Copyright Statement

   Copyright (C) The Internet Society (2003). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assignees.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION



Olson                  Expires December 21, 2003               [Page 18]

Internet-Draft    Extensions to the Dialog event package for Third Party Call Control                                            June 2003


   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.











































Olson                  Expires December 21, 2003               [Page 19]