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
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 4579 (Best Current Practice) | |
| 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,
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