Recommendation ITU-T H.248.78 defines a package that allows bearer-level application protocol (such as real time streaming protocol (RTSP) or message session relay protocol (MSRP)) messages received by a media gateway (MG) to be communicated to a media gateway controller (MGC). This allows the MGC to perform application-level gateway functionality such as network address translation on the messages and then forward the messages to the MG for sending to the destination.
The (03/2013) revision incorporates an update to correctly refer to the "Message Session Relay Protocol".
This revision of Recommendation ITU-T H.248.78 adds a further H.248 package for support of
a) MG located application-level gateway functionality and
b) MG message backhauling functionality
It also updates the title from "bearer-level application level gateway" to "bearer-level message backhauling and application level gateway".