ITU-T H.248.78 PDF

In a split media gateway controller (MGC) and media gateway (MG) environment, call-level application level gateways (ALG) are common in order to translate address information (i.e., network address and port translation (NAPT)) between two signalling domains. Typically, the application signalling traverses the MGC. ITU-T H.248 is therefore not involved in these translations other than to set the necessary media transport parameters on applicable terminations.

Increasingly bearer-level application control signalling is being used which instead traverses the MG. This bearer-level application signalling typically is used within a session that has been established by the MGC; thus, some coordination between the two levels is needed.

This Recommendation provides functionality that allows the MGC and MG to coordinate bearer-level application level gateway functionality.