The present document provides the protocol details and example call flows for providing supplementary service to mobile users connected to Multimedia Domain (MMD) subsystem based on the Session Initiation Protocol (SIP) and the Session Description Protocol (SDP).

The present document is applicable to User Equipment (UEs), Application Servers (AS), Media Resource Function Controller (MRFC), and Media Resource Function Processor (MRFP). The function split between the AS and the MRFC is out of scope of this document. As a result, the procedures for the MRFC are described together with those for the AS.