Abstract: A multiprocessor subsystem, for a portion of the public switched telephone network (PSTN) conforming to architectural standards for advanced intelligent networks (AIN), contains processor elements for participating in management of call routing/switching processes, and other processor elements for participating in management of services provided to PSTN users and subscribers. The processors participating in call routing processes are tightly concentrated to ensure reliable control of respective processes, while the processors participating in management of user services are distributed so as to allow for virtually unlimited growth in new type services without potentially disrupting existing call traffic. This subsystem also contains processor elements having interfaces to networks external to the PSTN; e.g. data networks such as the Internet and World Wide Web, and pager networks.