Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents
RFC 4579
Document | Type |
RFC - Best Current Practice
(August 2006; No errata)
Also known as BCP 119
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Authors | Alan Johnston , Orit Levin | ||
Last updated | 2015-10-14 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4579 (Best Current Practice) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Allison Mankin | ||
Send notices to | rohan@ekabal.com, dean.willis@softarmor.com |
Network Working Group A. Johnston Request for Comments: 4579 Avaya BCP: 119 O. Levin Category: Best Current Practice Microsoft Corporation August 2006 Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents Status of This Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This specification defines conferencing call control features for the Session Initiation Protocol (SIP). This document builds on the Conferencing Requirements and Framework documents to define how a tightly coupled SIP conference works. The approach is explored from the perspective of different user agent (UA) types: conference- unaware, conference-aware, and focus UAs. The use of Uniform Resource Identifiers (URIs) in conferencing, OPTIONS for capabilities discovery, and call control using REFER are covered in detail with example call flow diagrams. The usage of the isfocus feature tag is defined. Table of Contents 1. Introduction ....................................................2 2. Terminology .....................................................3 3. SIP User Agent Conferencing Capability Types ....................3 3.1. Focus UA ...................................................4 3.2. Conference Factory URI .....................................4 3.3. Conference-Unaware UA ......................................5 3.4. Conference-Aware UA ........................................5 4. Usage of the 'isfocus' Feature Parameter ........................6 4.1. General ....................................................6 4.2. Session Establishment ......................................6 4.3. Discovery ..................................................7 5. SIP Conferencing Primitives .....................................7 5.1. INVITE: Joining a Conference Using the Conference Johnston & Levin Best Current Practice [Page 1] RFC 4579 SIP CC Conferencing for UAs August 2006 URI - Dial-In ..............................................7 5.2. INVITE: Adding a Participant by the Focus - Dial-Out ......11 5.3. INVITE: Manually Creating a Conference by Dialing In to a Conferencing Application ..........................15 5.4. INVITE: Creating a Conference Using Ad-Hoc SIP Methods ....16 5.5. REFER: Requesting a Focus to Add a New Resource to a Conference (Dial Out to a New Participant) ..............18 5.6. REFER: Requesting a User to Dial in to a Conference Using a Conference URI ....................................21 5.7. REFER with REFER: Requesting a Focus to Refer a Participant to Dial in to the Conference ..................23 5.8. Join Header Field: Dialing in to a Conference Using a (3rd Party) Dialog Identifier .....................26 5.9. Replaces Header Field: Switching User Agents within a Conference .......................................28 5.10. Replaces Header Field: Transferring a Point-to-Point Session in to a Conference ...............................29 5.11. REFER with BYE: Requesting That the Focus Remove a Participant from a Conference ............................31 5.12. Deleting a Conference ....................................33 5.13. Discovery of URI Properties Using OPTIONS ................34 6. Security Considerations ........................................36 7. Contributors ...................................................37 8. References .....................................................38 8.1. Normative References ......................................38 8.2. Informative References ....................................38 Appendix A: Creating a Conference by a Conference-Unaware UA.......40 1. Introduction This specification uses the concepts and definitions from the high level requirements [14] and the SIP conferencing framework [8] documents. This approach is applicable to tightly coupled SIP conferences. In this architecture, a user agent (UA), known as a participant, establishes a SIP dialog with another UA, known as a focus. The focus is the central point of control, authentication, and authorization. This specification defines the operation of a focus and participant UAs. Note that only the signalling (SIP) needs to be centralized in this model; the media can be centrally mixed,Show full document text