A roaming gateway for support of advanced voice services while roaming in wireless communications systems. The roaming gateway supports push-to-talk (P2T) calls, or other advanced voice services, when P2T subscribers roam from their home network (i.e., a network operated by their service provider where the subscriber's profile resides) into a foreign network (i.e., a network operated by another service provider). The roaming gateway is a specialized version of a real-time exchange that is located in the home network and is connected to mobile switching centers in foreign networks, so that the mobile switching centers in the foreign networks need not be programmed for the advanced voice services.