Tuesday, August 5, 2008

7. Media Gateway Control Protocol (MGCP)

What is MGCP?
  • It is protocol used within a VoIP system
  • It was developed to address the demands of carrier-based IP telephone network.
  • Also a complementary protocol for H.323 and SIP, which was designed as an internal protocol between Media Gateway Controller and Media Gateway.
What does MGCP consists of?
  • It comprised o a Call Agent, one MG (media gateway) which performs the conversion of media signals between circuits and packets, and one SG (signaling gateway) when connected to the PSTN (Public Switched Telephone Network).
  • MGCP is widely used between elements of a decomposed multimedia gateway. The gateway has a Call Agent, which is comprised of the call control "intelligence" and a media gateway boasting the media functions, for example conversion from TDM voice to Voice over IP.
MGCP Connection

MGCP connection can be point to point or point to multipoint. Once there is a connection, data transfer takes place between the endpoints. In multipoint connections, it is set up between endpoint and a multipoint session. In multipoint connection, it can be created over various types of bearer network.

The Architecture of MGCP

  • The architecture does not involved in the frustrating work of encoding ,decoding and transfer of voice signals.
  • The MGCP call agent works as a software switch for the VoIP network,.
  • It does noting more than simply direct the media gateway and media signalling gateway which perform all the work.
  • The main task of Call Agent is to implement numerous possibilities in the protocol.
  • In every architecture, each and every components features a transaction ID, gets an anknowledgement and receives a responses.
The MGCP Packets
  • MGCP packets are generally found wrapped in UDP port 2427.
  • An MGCP packer can either be a command or a response.
  • Commands start with a four-letter verb while "responses" start with a three number response code.

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