A method for providing advanced intelligent network (AIN) supplementary services between an ITU H.323 endpoint and a service control point (SCP) having service logic programs (SLPs) and transaction capabilities applications part (TCAP) protocol support is described. The method preferably includes providing an ITU H.450 interface in the SCP, the ITU H.450 interface being capable of communicating with the ITU H.323 endpoint, and utilizing an ITU H.225 FACILITY message and an ITU H.450 application protocol data unit (APDU) to carry one or more of call-related information, operation codes and AIN messages between the ITU H.323 endpoint and the SCP. In a case in which the AIN supplementary services are not related to an existing ITU H.323 call, the ITU H.225 FACILITY message is empty. Alternatively, in a case in which the AIN supplementary services are related to an existing ITU H.323 call, the ITU H.225 FACILITY message is one of a variety of user-to-user information elements (UUIEs). The invented apparatus for supporting advanced intelligent network (AIN) supplementary services in a voice frame network preferably includes an ITU H.450.1 interface to a service control point (SCP), the SCP having also a transaction capabilities applications part (TCAP) interface to the public switched telephone network (PSTN), the SCP providing AIN supplementary services in a network environment compatible with an ITU H.323 endpoint, and an ITU H.323 endpoint interface for coupling to the ITU H.450 interface over the voice frame network, the ITU H.323 endpoint interface supporting an ITU H.450-based communications protocol.