2.8.15 Session Initiation Proposal Investigation (sipping)

NOTE: This charter is a snapshot of the 64th IETF Meeting in Vancouver, British Columbia Canada. It may now be out-of-date.
In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at:

       Additional SIPPING Web Page

Last Modified: 2005-11-04


Gonzalo Camarillo <gonzalo.camarillo@ericsson.com>
Dean Willis <dean.willis@softarmor.com>
Rohan Mahy <rohan@ekabal.com>

Transport Area Director(s):

Allison Mankin <mankin@psg.com>
Jon Peterson <jon.peterson@neustar.biz>

Transport Area Advisor:

Allison Mankin <mankin@psg.com>


Oscar Novo <Oscar.Novo@ericsson.com>

Mailing Lists:

General Discussion: sipping@ietf.org
To Subscribe: sipping-request@ietf.org
In Body: (un)subscribe
Archive: http://www.ietf.org/mail-archive/web/sipping/index.html

Description of Working Group:

The Session Initiation Protocol Project INvestiGation (SIPPING)
working group is chartered to document the use of SIP for several
applications related to telephony and multimedia, and to develop
requirements for extensions to SIP needed for those applications.
Such requirements will be referred to the SIP working group for
development of any new SIP method, header, or option-tag as described
in Change Policy for SIP (RFC 3467).

Guiding principles for the performance of SIPPING's work will include:

1. Documenting the requirements of specific chartered tasks.

2. Documenting the usage of SIP to solve real problems that need
to be solved in a standardized way. Examples of important
topics identified are the session policy architecture, allowing
network entities to convey policy into an User Agent's
activity; requirements analysis for session border
controllers to determine how best such devices can
operate with SIP usage; guidance on IPv4-IPv6
co-existence support by SIP and SIP-supported media; and
inclusion of real-time text conversation (ToIP), service
invocations benefitting hearing and speech impaired users,
and other SIP equal access services as requirements are proposed.

3. Looking for commonalities among the chartered tasks and ongoing
SIP-related development, as commonalities may indicate for general,
reusable functionality in SIP.

4. Describing the requirements for any extension determined to pass
there hurdles, and handing the development task to the SIP WG.

5. Developing procedures and requirements for configuration and
delivery of SIP User Profiles

Besides performing needed specification of several applications
of SIP, SIPPING can be seen as also working out use cases that
clarify the role of SIP in the Internet, and help to ensure that
Occam's razor is appropriately applied to SIP usage.

The security of all the deliverables will be of special importance.
The technology for security will be keyed from the SIP Security
specification within RFC 3261, and additional SIP specifications
as they apply.

Goals and Milestones:

Done  Submit Internet-Draft on SIP-Telephony Framework to IESG for consideration as a BCP
Done  Submit Internet-Draft on ISUP-SIP Mapping to IESG for consideration as Proposed Standard
Done  Submit Internet-Draft on Requirements for use of SIP to support telephony for the Hearing-Impaired to IESG for consideration as an Informational RFC
Done  Submit SIP 3rd party call control to IESG for consideration as BCP
Done  Submit Internet-Draft on 3G Requirements to IESG for consideration as an Informational RFC
Done  Submit Internet-Draft on Mapping ISUP Overlap Signaling to SIP to IESG for consideration as a Proposed Standard
Done  Submit Internet-Draft on Usage Guideline for Events (Subscribe-Notify) to IESG for consideration as an Informational RFC
Done  Submit Internet-Drafts Basic and PSTN Call Flows to IESG fro consideration as BCPs
Done  Requirements for Content Indirection in SIP
Done  Submit Message Waiting SIP event package to IESG for consideration as PS
Done  Using ENUM with SIP Applications to IESG for consideration as an Informational RFC
Done  Requirements for Reuse of Connections in SIP
Done  Submit Internet-Draft on T.38 Fax Call Flows to IESG for consideration as a BCP
Done  Requirements for SIP Request History
Done  Submit Internet-Draft on Requirements for AAA Application in SIP Telephony to IESG for consideration as an Informational RFC
Done  Sip Interworking with QSIG
Done  3pcc Transcoding to IESG as Info
Done  KPML to IESG as PS
Done  Conferencing Requirements to IESG as Info
Done  Conferencing Framework to IESG as Info
Done  Conferencing Call Control-Conferencing to IESG as BCP
Done  End-to-Middle Security Requirements to IESG as Info
Done  Configuration Framework to the IESG as a PS
Oct 2005  Revise Charter
Nov 2005  Requirements for Consent-based Communications in SIP to IESG as Info
Nov 2005  Submit I-D on Subscriptions to Ad-Hoc Resource Lists to the IESG as PS
Nov 2005  Submit I-D on Multiple REFER to the IESG as PS
Nov 2005  Submit I-D on Ad-Hoc Conferencing using URI lists to the IESG as PS
Nov 2005  Submit URI List Transport Mechanism to the IESG as PS
Nov 2005  Framework for Consent-based Communications in SIP to IESG
Nov 2005  Session Policy Requirements to IESG as Info
Dec 2005  Requirements on Trait-Based Authorization to IESG as Info
Dec 2005  Transcoding Framework to IESG as Info
Dec 2005  Transcoding with Conf Bridge to IESG as Info
Dec 2005  Service Quality Reporting to IESG as PS
Jan 2006  Session Independent Policy Mechanism to the IESG as PS
Jan 2006  Session Specific Policy Mechanism to the IESG as PS
Jan 2006  SIP Security Flows to IESG as Info
Feb 2006  SIP Service Examples to IESG as Info
Feb 2006  IPv6 Transition in SIP to the IESG as Info
Mar 2006  Revise Charter


  • draft-ietf-sipping-service-examples-09.txt
  • draft-ietf-sipping-cc-framework-05.txt
  • draft-ietf-sipping-nat-scenarios-03.txt
  • draft-ietf-sipping-dialog-package-06.txt
  • draft-ietf-sipping-conference-package-12.txt
  • draft-ietf-sipping-torture-tests-08.txt
  • draft-ietf-sipping-cc-transfer-05.txt
  • draft-ietf-sipping-qsig2sip-04.txt
  • draft-ietf-sipping-config-framework-07.txt
  • draft-ietf-sipping-cc-conferencing-07.txt
  • draft-ietf-sipping-conferencing-requirements-01.txt
  • draft-ietf-sipping-conferencing-framework-05.txt
  • draft-ietf-sipping-callerprefs-usecases-05.txt
  • draft-ietf-sipping-kpml-07.txt
  • draft-ietf-sipping-app-interaction-framework-05.txt
  • draft-ietf-sipping-reason-header-for-preemption-04.txt
  • draft-ietf-sipping-transc-framework-02.txt
  • draft-ietf-sipping-sos-01.txt
  • draft-ietf-sipping-uri-services-04.txt
  • draft-ietf-sipping-uri-list-conferencing-04.txt
  • draft-ietf-sipping-uri-list-message-04.txt
  • draft-ietf-sipping-uri-list-subscribe-04.txt
  • draft-ietf-sipping-multiple-refer-04.txt
  • draft-ietf-sipping-certs-02.txt
  • draft-ietf-sipping-consent-reqs-01.txt
  • draft-ietf-sipping-consent-framework-03.txt
  • draft-ietf-sipping-toip-03.txt
  • draft-ietf-sipping-spam-01.txt
  • draft-ietf-sipping-transc-conf-00.txt
  • draft-ietf-sipping-v6-transition-01.txt
  • draft-ietf-sipping-message-tag-00.txt
  • draft-ietf-sipping-gruu-reg-event-00.txt
  • draft-ietf-sipping-media-policy-dataset-00.txt

    Request For Comments:

    RFC3324 I Short Term Requirements for Network Asserted Identity
    RFC3351 I User Requirements for the Session Initiation Protocol (SIP) in Support of Deaf, Hard of Hearing and Speech-impaired individuals
    RFC3372 BCP Session Initiation Protocol (SIP) for Telephones (SIP-T): Context and Architectures
    RFC3398 PS Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping
    RFC3485 PS The Session Initiation Protocol (SIP) and Session Description Protocol (SDP) Static Dictionary for Signaling Compression (SigComp)
    RFC3578 PS Mapping of of Integrated Services Digital Network (ISUP) Overlap Signalling to the Session Initiation Protocol (SIP)
    RFC3665 BCP Session Initiation Protocol Basic Call Flow Examples
    RFC3666 BCP Session Initiation Protocol PSTN Call Flows
    RFC3680 Standard A Session Initiation Protocol (SIP) Event Package for Registrations
    RFC3702 I Authentication, Authorization and Accounting Requirements for the Session Initiation Protocol
    RFC3725 BCP Best Current Practices for Third Party Call Control in the Session Initiation Protocol
    RFC3824 I Using E.164 numbers with the Session Initiation Protocol (SIP)
    RFC3842 Standard A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)
    RFC3959 Standard The Early Session Disposition Type for the Session Initiation Protocol (SIP)
    RFC3960 I Early Media and Ringing Tone Generation in the Session Initiation Protocol (SIP)
    RFC4083 I Input 3rd-Generation Partnership Project (3GPP) Release 5 requirements on the Session Initiation Protocol (SIP)
    RFC4117 I Transcoding Services Invocation in the Session Initiation Protocol (SIP) Using Third Party Call Control (3pcc)
    RFC4189 I Requirements for End-to-Middle Security for the Session Initiation Protocol (SIP)

    Current Meeting Report

    SIPPING Minutes IETF64 Minutes SIPPING WG at IETF 64

    Minutes edited by Gonzalo Camarillo
    Based on notes by Hisham Khartabil, Dean Willis, Jim McEachern,
    Dorothy Gellert, and Steve S.
    Meeting chaired by Dean Willis, Rohan Mahy, and Gonzalo Camarillo
    Slides presented included in the proceedings

    MONDAY, November 7, 2005, 1510-1710

    Topic: Agenda Bash
    Discussions led by: Chairs

    Two ad-hoc meetings were announced: one on TISPAN-related issues and
    another on peer-to-peer SIP. Oscar Novo was presented as the new
    SIPPING secretary.

    The chairs presented the status of all the SIPPING WG items. The
    URI-list services drafts have passed WGLC and are ready, but they are
    waiting for the consent framework to be ready. New revisions of the
    RTCP summary and trait-based authorization drafts will be submitted
    shortly. The chairs will request their publication as soon as the new
    revisions appear in the archives.

    The chairs presented the updated charter and milestones. It was noted
    that the dialog usage draft has disappeared. The chairs will
    investigate what happened with that draft.

    Topic: Configuration Framework and Data Sets
    Discussion led by: Dan Petrie
    Relevant documents:

    There were discussions on whether the text on merging should be
    removed from the drafts. It seems easier to construct a data model
    such that merging is easy than provide all nodes with a general
    merging engine.

    There were discussions on how much XML validation should be required
    in the clients. The conclusion was to using the XML schema as used in
    SIMPLE. At this point, there are no requirements for strong XML
    validation at the client side.

    There were discussions without a clear conclusion on whether, for
    certain configuration data, user agents can be provided with the URI
    of a single hop or they need a routing vector.

    Data sets dealing with configurable elements defined by SIP or SIPPING
    WG items will be WG items as well.

    Topic: Session Policy Framework and Data Set Format
    Discussion led by: Volker Hilt
    Relevant documents:

    The chairs will add a milestone date for the session policy framework
    to the charter.

    There was consensus that using an SDP format for session specific
    policies would be OK.

    Topic: Consent Framework
    Discussion led by: Gonzalo Camarillo
    Relevant documents:

    There was consensus to remove the operations part from the permission
    documents. Furthermore, there was consensus on having permissions that
    are as simple as possible, given that they will be stored by servers
    that do not any relation with the users uploading them.

    Topic: Conference Bridge Transcoding Model
    Discussion led by: Gonzalo Camarillo
    Relevant documents:

    The author will clarify how transcoders create their offers.

    Topic: IPv6 Transition
    Discussion led by: Vijay Gurbani
    Relevant documents:

    The topic of using TURN for IPv4/IPv6 transition will be further
    discussed in the BEHAVE WG. Agreed that the draft should not contain
    examples of network APIs.

    It was noted that some interactions between DNS and dual-stack SIP
    nodes could also belong to a future update of RFC 3263. It was
    suggested to remove the general discussions on IPv6 transition
    strategies from the draft.

    The WG is interested in working on this, but remains undecided as to
    whether to schedule this work immediately or defer it for a future

    Topic: SIP-unfriendly Functions in Current Architectures
    Discussion led by: Jani Jautakorpi
    Relevant documents:

    It was noted that this draft is not only useful for SBC implementers,
    but also for UA implementers. Therefore, it is a good thing that the
    draft is not only focused on SBCs.

    It was suggested to document the requirements for features that SBCs
    currently implement, how they are currently implemented, and how those
    implementations break SIP. With all these things documented, the draft
    would be useful to start new work that meets those requirements in a
    more SIP-friendly way. The chairs will meet the authors to align
    terminology and to determine the scope of the draft.

    A few people agreed to send comments to the authors and to the list on
    the examples in the draft.

    There seems to be agreement that this document is useful and that
    should eventually become an RFC.

    Topic: Max Forwards Issues
    Discussion led by: Robert Sparks
    Relevant documents:

    It was noted that loop detection would eliminate this problem. There
    could be ways of implementing loop detection that require less state
    information than the current proposals.

    It was noted that RFC 3261 specifies loop detection for proxies, but
    does not require its usage.

    It was suggested that other solutions to this problem could consist of
    limiting arbitrary registrations of contacts or limiting inter-domain
    forking somehow.

    It was concluded that his discussion should continue in the SIP WG
    since this is a bug in RFC 3261.

    Topic: Multi Transcoding
    Discussion led by: Tae-Gyu Kang
    Relevant documents:

    The draft deals with the following use case: if a call is placed
    through a transcoder, and the transcoder cannot complete an
    offer/answer exchange with the next hop, then a 488 response would
    indicate a problem with the transcoder, not with the "far side". This
    may justify a new response code.

    The author will need to clarify what is the use case that gets us into
    a situation with more than one or two transcoders when using the
    conference bridge transcoding model (which is intended for simple

    The first SIPPING session ended.

    WEDNESDAY, November 9, 2005, 1300-1500

    Topic: Redirection Issues
    Discussion led by: John Elwell
    Relevant documents:

    The draft was not presented. The chairs informed the group that the
    authors have realized that their requirements can be met by slightly
    modifying draft-jennings-sip-voicemail-uri-04.txt.

    There was a discussion on the path for this draft, which will be AD
    sponsored informational.

    Topic: Extending the SIP Reason Header with Warning Codes
    Discussion led by: Jani Hautakorpi
    Relevant documents:

    The authors clarified that the main purpose of this draft was to
    trigger discussions on the usage of Warning header fields in SIP. At
    this point, not many implementers use them, and according to RFC 3261,
    their scope is limited to reporting problems related to session

    It was noted that external SDOs are planning to propose SIP extensions
    in the near future and they need to know whether proposing new Warning
    codes to meet their requirements is appropriate, or if they should
    propose new response codes instead.

    There were discussions on whether or not response codes are
    enough. The conclusion seemed to be that they are enough and that we
    should not encourage new Warning code definitions at this point. In
    any case, this discussion will be continued on the list.

    There were discussions on whether the response code address space is
    running out. Robert Sparks agreed to look into all the new response
    codes being proposed (otherwise, they are not registered in the IANA
    until they are documented in an RFC).

    Topic: GRUU Reg Event Package
    Discussion led by: Paul Kyzivat
    Relevant documents:

    Consensus to go with the draft as is and schedule its WGLC.

    Topic: Requirements and Possible Mechanisms for File Transfer Services
           Within the Context of SIP Based Communication
    Discussion led by: Markus Isomaki
    Relevant documents:

    There were discussions on whether or not this work is useful and, if
    it is, where should this work proceed. The conclusion was to write a
    requirements document and discuss it in SIPPING.

    Topic: SIP Identity Usage within Enterprise Scenarios
    Discussion led by: Steffen Fries
    Relevant documents:

    There were discussions on the difference between device certificates
    and user certificates. The topic needs to be clarified so that
    everybody can understand it.

    Topic: Calling Party Category
    Discussion led by: Rocky Wang
    Relevant documents:
    There were discussions on whether it would make sense to do this with
    SAML. The author will talk to the folks working on SAML.

    Topic: Implementations of PRACK
    Discussion led by: Rohan Mahy

    In the MMUSIC session, some folks mentioned that people were trying
    and avoiding implementing PRACK due to its complexity. There were some
    discussions on what to do without a clear conclusion.

    Topic: Payment for Services in SIP
    Discussion led by: Jason Fischl
    Relevant documents:

    There were discussions on whether this work is useful for things that
    are not SPIT or SPAM. It was proposed to use SAML, but not many people
    were up to date with SAML.

    Topic: URN for Services
    Discussion led by: Henning Schulzrinne
    Relevant documents:

    It was concluded that this work should continue in the ECRIT WG.

    The second SIPPING session ended.

    The SIPPING WG organized two ad-hoc meetings during the week of the
    IETF meeting. The minutes of the ad-hoc meeting on TISPAN-related issues can be
    found here. The minutes of the ad-hoc meeting on peer-to-peer SIP issues can be
    found here.


    Agenda and Status
    Config Issues and Profile Datasets
    Session Policy
    SIP Unfriendly Functions in SBCs
    Transcoding Scenarios
    Registration Event Package with GRUU
    Reason with Warnings
    File Transfer
    Identity in Enterprise Scenarios
    Calling Party Category
    Payment for Services in SIP
    PRACK issues
    ISDN Simulation for ETSI TISPAN