E.4.2.3 Transport of H.245 messages between the MGCF and IM-MGW

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

E.4.2.3.1 General

H.245 messages shall be transported between the IM-MGW and MGCF over the Mn interface using H.248 Events (from the IM‑MGW towards the MGCF) and H.248 Signals (from the MGCF towards the IM-MGW). The Events/Signals shall contain the following information:

– H.245 message (binary).

E.4.2.3.2 Transport from MGCF to IM-MGW

Figure E.4.2.3.2.1: Mn signalling interactions for sending H.245 message

In Signal 1, the MGCF requests the IM-MGW to send an H.245 message to the CS side. To request the IM-MGW to send a H.245 message to the CS side, the MGCF shall sent an H.248 signal to the IM-MGW with the complete H.245 message content.

NOTE: In order for this command to succeed, Termination T1 towards the CS side needs to be configured. If a sending of an H.245 message and a removal of termination T1 is desired, the MGCF needs to apply signal 1 before removing T1.

Upon reception of this signal, the IM-MGW shall send the encapsulated H.245 message within the H.248 signal, through the H.245 control channel to the CS side (signal 3).

E.4.2.3.3 Transport from IM-MGW to MGCF

Figure E.4.2.3.3.1: Mn signalling interactions for receiving H.245 message

In signal 1, the MGCF requests the IM-MGW to detect received H.245 message from the CS side and forward them to the MGCF. To request the IM-MGW to detect and forward a H.245 message to the CS side, the MGCF shall send a suitable H.248 event to the IM-MGW. The event may be indicated through an H.248 ADD command.

In signal 3, the IM-MGW receives an H.245 message from the CS side. Upon reception of an H.245 message from the CS side, the IM-MGW shall de-multiplex the H.245 message from the H.223 stream and forward the H.245 message to the MGCF within an H.248 Notify command (signal 4).