Media Gateway Control Protocol

Media Gateway Control Protocol also known as MGCP is one of the implementation of the Media Gateway Control Protocol Architecture for controlling media gateways on Internet Protocol (IP) networks and the public switched telephone network (PSTN). The general base architecture and programming interface is described in RFC 2805 and the current specific MGCP definition is RFC 3435 (obsoleted RFC 2705). It is a successor to the Simple Gateway Control Protocol (SGCP) which was developed by Bellcore and Cisco. In November 1998, Simple Gateway Control Protocol (SGCP) was combined Level 3 Communications Internet Protocol Device Control (IPDC), to form Media Gateway Control Protocol MGCP.

MGCP is a signalling and call control protocol used within Voice over IP (VoIP) systems that typically inter-operate with the public switched telephone network (PSTN). As such it implements a PSTN-over-IP model with the power of the network residing in a call control center (softswitch, similar to the central office of the PSTN) and the endpoints being "low-intelligence" devices, mostly simply executing control commands. The protocol represents a decomposition of other VoIP models, such as H.323, in which the media gateways (e.g., H.323's gatekeeper) have higher levels of signalling intelligence.

MGCP uses the Session Description Protocol (SDP) for specifying and negotiating the media streams to be transmitted in a call session and the Real-time Transport Protocol (RTP) for framing of the media streams.

Another implementation of the Media Gateway Control Protocol Architecture which exists is the H.248/Megaco protocol, a collaboration of the Internet Engineering Task Force (RFC 3525) and International Telecommunication Union (Recommendation H.248.1). Both protocols follow the guidelines of the API Media Gateway Control Protocol Architecture and Requirements in RFC 2805. However, the protocols are incompatible due to differences in protocol syntax and underlying connection model.