Session Initiation Protocol Call Control - Conferencing for User Agents

Document Type Expired Internet-Draft (individual)
Author Orit Levin 
Last updated 2003-02-11
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document 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 different user agent (UA) types perspective: conference-unaware, conference-aware and focus UAs. The use of URIs in conferencing, OPTIONS for capabilities discovery, and call control using REFER are covered in detail with example call flow diagrams.


Orit Levin (

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