- This document defines the protocol used between elements of a physically decomposed multimedia gateway. There are no functional differences from a system view between a decomposed gateway, with distributed sub-components potentially on more than one physical device, and a monolithic gateway such as described in H.246. This document does not define how gateways, multipoint control units or interactive voice response units (IVRs) work. Instead it creates a general framework that is suitable for these applications. Packet network interfaces may include IP, ATM or possibly others. The interfaces will support a variety of SCN signalling systems, including tone signalling, ISDN, ISUP, QSIG, and GSM. National variants of these signalling systems will be supported where applicable.