MGCP is Master/Slave protocol and MGCP endpoints are controlled by the Control Agent ( Most of the case , it will be the CUCM)
MGCP uses the UDP/2427 for its communication between the CUCM and the GW. It is also a text-based master/slave protocol used by a media gateway controller (MGC) and Call Agent to control media gateways. However , TCP/2428 is used to exchange keepalives between endpoints and Call Agent, as well for MGCP PRI/BRI backhaul.
MGCP MGCs and MGs can be described as follows:
- MGC/Call Agent: this element possesses call control intelligence and controls MGs (example : Call Manager)
- MG: This device provides translation between data packet and audio signals reveived over VoIP networks and other networks such as the PSTN ( example: IOS gateway)