General: MGCP stands for Media Gateway Control Protocol. It’s a client-server protocol which means that it has to depend on Media Controller (Call agent) for call routing. In case of Cisco this MC is a CUCM. The Call agent controls the ports of a MGCP gateway. UDP Port 2427 is used for communication between Call manager and Gateway. TCP port 2428 is used for PRI Backhauling and Keepalives from Gateway to Call manager. PRI backhauling is process where layer 3 information is passed back to Call manager while layer 2 stays at the gateway. Prior to Call manager 3.1, gateway … Continue reading MGCP – How it works?