A Call Control and Multi-Party Usage Framework for the Session Initiation Protocol (SIP)
RFC 5850

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Internet Engineering Task Force (IETF)                           R. Mahy
Request for Comments: 5850                                  Unaffiliated
Category: Informational                                        R. Sparks
ISSN: 2070-1721                                                  Tekelec
                                                            J. Rosenberg
                                                             jdrosen.net
                                                               D. Petrie
                                                                   SIPez
                                                        A. Johnston, Ed.
                                                                   Avaya
                                                                May 2010

           A Call Control and Multi-Party Usage Framework for
                 the Session Initiation Protocol (SIP)

Abstract

   This document defines a framework and the requirements for call
   control and multi-party usage of the Session Initiation Protocol
   (SIP).  To enable discussion of multi-party features and
   applications, we define an abstract call model for describing the
   media relationships required by many of these.  The model and actions
   described here are specifically chosen to be independent of the SIP
   signaling and/or mixing approach chosen to actually set up the media
   relationships.  In addition to its dialog manipulation aspect, this
   framework includes requirements for communicating related information
   and events such as conference and session state and session history.
   This framework also describes other goals that embody the spirit of
   SIP applications as used on the Internet such as the definition of
   primitives (not services), invoker and participant oriented
   primitives, signaling and mixing model independence, and others.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5850.

Mahy, et al.                  Informational                     [Page 1]
RFC 5850               SIP Call Control Framework               May 2010

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   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   Without obtaining an adequate license from the person(s) controlling
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   than English.

Table of Contents

   1.  Motivation and Background  . . . . . . . . . . . . . . . . . .  4
   2.  Key Concepts . . . . . . . . . . . . . . . . . . . . . . . . .  6
     2.1.  Conversation Space Model . . . . . . . . . . . . . . . . .  7
     2.2.  Relationship between Conversation Space, SIP Dialogs,
           and SIP Sessions . . . . . . . . . . . . . . . . . . . . .  8
     2.3.  Signaling Models . . . . . . . . . . . . . . . . . . . . .  9
     2.4.  Mixing Models  . . . . . . . . . . . . . . . . . . . . . . 10
       2.4.1.  Tightly Coupled  . . . . . . . . . . . . . . . . . . . 11
       2.4.2.  Loosely Coupled  . . . . . . . . . . . . . . . . . . . 12
     2.5.  Conveying Information and Events . . . . . . . . . . . . . 13
     2.6.  Componentization and Decomposition . . . . . . . . . . . . 15
       2.6.1.  Media Intermediaries . . . . . . . . . . . . . . . . . 15