E.2.2 Functionalities required in the MGCF for multimedia calls support

29.1633GPPInterworking between the IP Multimedia (IM) Core Network (CN) subsystem and Circuit Switched (CS) networksTS

In addition to the control plane Interworking between SIP and ISUP or BICC, the MGCF needs to mediate interactions between the H.245 signalling or MONA (Media Oriented Negotiation Acceleration) procedures at the CS side and SIP/SDP signalling at the IMS side. The interactions between H.245 signalling or MONA procedures and SIP/SDP signalling should aim at avoiding media transcoding by selecting the same codec for the CS side and the PS side.

NOTE: Detailed procedures for the mapping between SDP parameters and H.245 parameters are not specified in the present release.