They interwork through the Mc interface, which is the standard interface of the control layer and bearer layer in the core network. The Mc interface adopts the extended H.248 protocol defined by the ITU-T. Through the Mc interface, the MSOFTX3000 controls the bearer resources at the radio access side and trunk side. The interface is an IP-based interface added in the R4 stage.

H.248 Protocol: H.248 or Megaco or Gateway Control Protocol is a recommendation from ITU Telecommunication Standardization Sector (ITU-T) which defines protocols that are used between elements of a physically decomposed multimedia gateway. It is an implementation of the Media Gateway Control Protocol Architecture (RFC 2805). H.248 is also calledMegaco in IETF domain. It is now known as Gateway Control Protocol. The current standard published in September 2005 by ITU-T is H.248.

Mc interface: Interface used between MGW & Server

R4 stage: A UMTS R4 network is designed in the BICC structure so that new services can be easily applied. The core network adopts packet bearer mode, which occupies less bandwidth.

This document is very well done

very generic across operators, thanks for the post.

Nice update

H.248 protocol:  Media Gateway Control Protocol (MGCP), also known as H.248 and Megaco, is a standard protocol for handling the signaling and session management needed during a multimedia conference. The protocol defines a means of communication between a media gateway, which converts data from the format required for a circuit-switched network to that required for a packet-switched network and the media gateway controller. MGCP can be used to set up, maintain, and terminate calls between multiple endpoints. Megaco and H.248 refer to an enhanced version of MGCP.

Can you update more on H.248 protocol?

What is Mc interface?