The present invention provides a system and method enabling telephony service subscribers to activate, deactivate, make service changes, and access call-related information from telephony services provided by a telephony service provider. According to one aspect, the service management system of the present invention interacts with subscriber terminals connected to a public data network. The service management system receives requests from subscriber terminals and converts the requests into a format compatible with terminal emulation programs, such as the Telnet protocol, running on end office switches. Using the converted request information, the requested service changes are made or the requested call-related information is collected by the end office switches with little or no intervention by service provider personnel.