Alcatel Cisco A Media Gateway with ISDN terminations will use both Megaco [1] and Sigtran protocols for communication with the Media Gateway Controller. In an ISDN Access Gateway the media carrying B-channels are controlled by the Media Gateway Controller using Megaco, while the User-to-Network signalling running over the D-channels will be relayed to the Media Gateway Controller using Sigtran protocols (IUA [3] over SCTP [2]). At the moment, in the absence of appropriate specifications, the Megaco and Sigtran protocols may interact in different ways in the Access Gateway, leaving room for non-interoperable solutions. This draft proposes a set of guidelines for the Megaco-Sigtran interworking, documenting a best current practice for ISDN Access Gateways.