A session initiation protocol (SIP) based communication system registers a number of different device types (10, 50) in a database (30). Each type of communication device is registered including a communication device description, internet protocol address, priority, registration time, and expiration time (80). When a call is received by the network (20), the communication device at which to reach the user is first selected by priority (116) and then by registration time of the communication device (122).