In conventional telephone services, methods of response to a call in cases where the destination caller cannot answer the call are limited, such as by playing back an answering machine message or transferring the call to another telephone system in a rigid manner. In such systems, there is no flexibility in choosing the manner of response depending on the situation of the destination caller. The example systems and methods described herein enable the response method to be automatically selected depending on user's current position information in an Internet telephone system in which voice data is transmitted and received via the Internet. The user registers response methods associated with network addresses in a database, and the user's current position is determined from the IP address.