This TS specifies the stage three Protocol Description of the Conference (CONF) service based on stage one and two of the ISDN CONF supplementary service. It provides the protocol details in the IP Multimedia (IM) Core Network (CN) subsystem based on the Session Initiation Protocol (SIP) and the Session Description Protocol (SDP).
This TS specifies centralized conferencing, using a conference focus, distributed conferencing is out of scope.
This TS does not cover the cases of :
cascading conference services; and
the support of the PSTN/ISDN conference service hosted in the PSTN.
This TS is applicable to User Equipment (UE) and Application Servers (AS) which are intended to support the CONF supplementary service.