The present document provides the protocol details for conferencing within the IP Multimedia Core Network Subsystem (IMS) based on the Session Initiation Protocol (SIP), SIP Events and the Session Description Protocol (SDP).

The functionalities for conference policy control and for floor control (with respective standardised protocols) are felt to be essential for a complete IMS conferencing service but are not specified in this version of IMS conferencing and are for further study.

The present document does not cover the signaling between a MRFC and a MRFP.

Where possible, the present document specifies the requirements for this protocol by reference to specifications produced by the IETF within the scope of SIP, SIP Events and SDP, either directly, or as modified by 3GPP2 X.S0013-004-A. Where this is not possible, extensions to SIP are defined within the present document. The document has therefore been structured in order to allow both forms of specification.

The present document is applicable to Application Servers (ASs), Multimedia Resource Function Controllers (MRFCs), Multimedia Resource Function Processors (MRFP), Media Gateway Control Functions (MGCFs) and to User Equipment (UE) providing conferencing capabilities.