VoIP and Voice over WLANs
MGCP and H.248/Megaco

Media Gateway Control Protocol (MGCP), also known as IETF RFC 2705, defines a centralized architecture for creating multimedia network applications, including VoIP.

H.248 is the result of a joint collaboration between the ITU-T and the Internet Engineering Task Force (IETF). H.248 is also referred to as IETF RFC 2885 and as the Multimedia Gateway Control Protocol (Megaco). H.248 also defines a centralized architecture for creating multimedia applications. In many ways, H.248 builds on and extends MGCP.

MGCP and H.248/Megaco were designed to provide architecture in which call control and services could be centrally added to a VoIP network. An architecture using these protocols closely resembles the existing PSTN architecture and services.

MGCP and H.248/Megaco define most aspects of signaling using a model called packages. These packages define commonly used functionality, such as PSTN signaling, line-side device connectivity, and features such as transfer and hold. SDP is also used for capabilities exchange.

In a centralized architecture, MGCP and H.248/Megaco allow companies 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.