- Media Gateway Control Protocol (Megaco)
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Megaco (officially H.248) is a gateway control protocol.[1] and an implementation of the Media Gateway Control Protocol architecture[2] for controlling media gateways in Internet Protocol (IP) networks and the public switched telephone network (PSTN). It is for the control of elements of a physically decomposed multimedia gateway, which enables separation of call control from media conversion.[3] Though H.248 performs the same functions as MGCP, it uses different commands and processes and supports a broader range of networks. H.248 can operate with H.323 orSIP.[4]
H.248 is meant to address the relationship between the Media Gateway, which converts circuit-switched voice to packet-based traffic, and the Media Gateway Controller.[5] H.248 instructs an MG to connect streams coming from outside a packet or cell data network onto a packet or cell stream such as the Real-Time Transport Protocol.[5]
The general base architecture for the Media Gateway Control Protocol and programming interface was originally described in RFC 2805 and the current specific Megaco definition is ITU-T Recommendation H.248.1.
Megaco defines the protocol for media gateway controllers to control media gateways for the support of multimedia streams across computer networks. It is typically used for providing Voice over Internet Protocol (VoIP) services (voice and fax) between IP networks and the PSTN, or entirely within IP networks.
The protocol was the result of collaboration of the MEGACO working group of the Internet Engineering Task Force (IETF) and International Telecommunication Union ITU-T Study Group 16. The IETF originally published the standard as RFC 3015, which was later replaced by RFC 3525. The term Megaco is the IETF designation. The ITU later took ownership of the protocol and IETF's version has been reclassified as historic. The ITU has published three versions of H.248.1, the most recent in September 2005.
H.248 encompasses not only the base protocol specification in H.248.1, but many extensions defined throughout the H.248 Sub-series.
Another implementation of the Media Gateway Control Protocol architecture exists in the similarly named MGCP protocol. This is used over the same interface and similar in application and service functionality, however, it is a different protocol and the underlying differences make them incompatible.
See also
References
External links
- ITU-T H-series Recommendations ITU-T Publication site where the H-series, including the H.248 Sub-series, Recommendations can be downloaded in PDF format free of charge.
- H.248.1.
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