The Media Gateway Control protocol (Megaco) is a result of joint efforts of the IETF and the ITU-T (ITU-T Recommendation H.248). Megaco/H.248, based on the Media Gateway Control Protocol (MGCP), is designed to provide an architecture where call control and services could be centrally added to a VoIP network. Megaco/H.248 allows companies or service providers to build large-scale networks that are scalable, resilient, and redundant. It provides mechanisms for interconnecting with other VoIP networks and for adding intelligence and features to the call agent or media gateway controller. In the Megaco/H.248 architecture, the call control intelligence is located outside the gateways and is handled by the media gateway controller(or Call Agent). Also, the call agent will synchronize with each other to send coherent commands to the gateways under their control. CableLab has adopted the MGCP for its PacketCable embed clients in VOIP applications and the resulted protocol is called Network Based Signaling Protocol (NCS). Megaco/H.248 is essentially quite similar to MGCP from an architectural standpoint and the controller-to-gateway relationship but Megaco/H.248 supports a broader range of networks.

Gateway Control Protocols (GCPs) supports a centralized VOIP Network. The key components of GCP Network are:

• Media Gateway Controller(MGC): also known as Call Agent or Softswitch, an element controls a number of dumb terminals and the Media Gateways. The MGC receives signaling information from the Media Gateway and can instruct it to alert the called party, to send and receive voice data etc.
• Media Gateway(MG): acts as a translation unit between disparate telecommunications networks such as PSTN; IP Networks; Mobile access networks or PBX.
• Signaling Gateway (SG): A component responsible for translating signaling messages between IP network and PSTN.
• Endpoints: Provide audio, data and video communications with another GCP terminal or a PSTN phone via gateway.

MGCP Documents

H.248/Megaco Standards

Main difference between Megaco/MGCP

MGCP Architecture

Related Terms: MGCP, GCP, Media Gateway Control Protocol, Gateway Control Protocol, Megaco, H.248

Reference Links: http://www.javvin.com/protocolVOIP.html: VOIP Protocols