Gateway control signalling traffic is carried over a transport connection between the media gateway controller (MGC) and media gateway (MG). Recommendation ITU-T H.248 supports multiple, different transport technologies. Each possible protocol stack variant is called ITU-T H.248 transport mode.

Recommendation ITU-T H.248.67 contains an ITU-T H.248 package to determine the supported transport modes by a MG and the indication of a preferred mode. The package enables an MGC to audit and change the transport mode. Transport mode changes may be driven by network evolution, i.e., transitioning from IP version 4 to IP version 6 environments. The added value of this package is given by the capability to support online transport mode changes.