Abstract: An action control point master gatekeeper for a communications network creates a hierarchical scalable signaling and transaction infrastructure for supporting carrier level deployment of, for example, IP telephony using H.323 terminals and gateways. The action control point master gatekeeper supports a plurality of H.323 zones in an administrative domain. Action control point master gatekeepers in an administrative domain can signal to other administrative domains via a hierarchical signaling infrastructure. A backup master gatekeeper can also be present in an action control point. A customer database, which can be distributed within zones or centralized within an administrative domain, allows for address resolution between a terminal alias and a terminal address. The customer database can also contain pointers to special purpose processes, such as network control points, to implement service specific transaction services.