H.248

The Media Gateway Control Protocol ( Megaco ) is a by the IETF (RFC 3015, RFC 3525 later ) and the ITU -T ( Recommendation H.248 ) jointly developed gateway protocol for controlling media gateways (MG) ​​and is for the construction used by VoIP connections. It operates independently of signaling protocols such as the network protocol H.323 and Session Initiation Protocol (SIP). It mainly supports the SIGTRAN signaling (IETF) group and represents the voice channel control for this ready. However, it can also transport simple signaling for analog devices, as long as they are limited to the transmission of alphanumeric characters { 0,1,2 ... E, F} ( telephonic digits ). The ITU has now fully taken over the protocol, the IETF set to support the protocol (see RFC 5125 ).

MEGACO is essentially based on the principle that all the intelligence of the call control in the media gateway controller (MGC) is concentrated. The Media Gateway itself does not retain any information about the current state of the connection establishment, it is primarily the ability to connect different types of media to connect streams and signaling, which is associated with these streams to be transmitted.

MEGACO considered the media gateway as a collection of terminations, each of which represents a particular type of media streams. Termination here means a physical entity such as an analog phone line or a B channel of ISDN. However, it can be a boolean function unit also, such as a VoIP Packet Stream. Such logical functional units are software- based and can be created and deleted using the Megaco protocol in the media gateway.

Megaco/H.248 enable media gateway controllers to control the Media Gateways. The Megaco/H.248 corresponds to the functions of the Media Gateway Control Protocol ( MGCP ) and provides the necessary control functions of IP phones that operate in master -slave operation. Additionally the protocol for peer-to -peer interoperability. It decomposes the H.323 function in subcomponents and specifies the protocols used for the respective communication processes each component.

The Media Gateway Control Protocol is an earlier predecessor specification by IETF and was compared with the later Megaco significant limitations in scheduling control and their groupings in contexts for a single call.

  • Network protocol
  • Switching technology
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