scope:

The present document defines call control protocols and procedures for use in the IMS-based PSTN/ISDN Emulation subsystem based on the Media Gateway Control Protocol (MEGACO), the Session Initiation Protocol (SIP), and the associated Session Description Protocol (SDP).

NOTE: The present document relies on the architectural framework defined in TS 182 012 [3] for IMS-based PES Emulation and may need to be updated once the open issues identified in the present document are resolved.

The present document is applicable to:

the interface between the User Equipment (UE) and the Call Session Control Function (CSCF);

the interface between the Access Gateway Control Function (AGCF) and the Media Gateway Function (MGF);

the interface between the Access Gateway Control Function (AGCF) and the Call Session Control Function (CSCF);

the interface between the CSCF and any other CSCF;

the interface between the CSCF and an Application Server (AS);

the interface between the CSCF and the Media Gateway Control Function (MGCF);

the interface between the S-CSCF and the Multimedia Resource Function Controller (MRFC);

the interface between the CSCF and the Breakout Gateway Control Function (BGCF);

the interface between the BGCF and the MGCF;

the interface between the BGCF and any other BGCF;

the interface between the CSCF and an external Multimedia IP network;

the interface between the CSCF and the IBCF;

the interface between the CSCF and the IBCF.