An enhanced computer telephony integration system that facilitates the interaction and integration of a private branch exchange (PBX) with a client computer on a computer network. An enhanced telephony (ET) server connects to the PBX and to all running instances of an ET client on a user's computers. The ET server acts as a proxy between the ET clients and the PBX. The ET clients register with the ET server for a certain telephone extension. The ET server then can forward telephone action requests (such as placing a telephone call) from the registered ET clients to the PBX servicing the telephone extension. Moreover, the ET server can relay telephone events (such as an incoming call) from the PBX to all registered clients. The ET server facilitates seamless integration of telephone and personal computer features to provide a rich user-controlled computer-telephone integration for a user.