Abstract: A system and method of PSTN based network roaming and SCP based subscriber management for internet telephony systems. When a call is incoming to the central office 60 of a subscriber's home service area which supports packet data network telephony 10, such as for instance IP telephony, a home location register 40 translates the directory number into an IP address, URL address, or electronic mail address much the same that a local number portability node re-routes calls for non-IP telephony systems. When a subscriber is roaming in another network 100, the roamed into (visited) gateway 130 signals back to the home location register 40 of the subscriber's network 20 and registers its (i.e., the visited gateway's) public switching telephone network 70 telephone directory number and the IP address assigned to the subscriber while connected to the visited network 100.