Patent ID: 7292566

Claim:
A telephone terminal having a plurality of transmitter/receiver units, to each of which identifying information on Internet is assigned, and a base unit for inputting/outputting audio signals transmitted through Internet to relay the audio signals to the transmitter/receiver unit, wherein the base unit comprises: an inquiry device that inquires a state of use to the transmitter/receiver unit, to which the identifying information is assigned, when an incoming call based on the identifying information is received through Internet; a determination device that determines whether a voice call through the transmitter/receiver unit is available based on the state of use responded to the inquiry by the inquiry device; and a call response device (i) that calls the transmitter/receiver unit to perform a voice call with a calling party through Internet, when the determination device determines that the voice call through the transmitter/receiver unit is available, (ii) that outputs the message to the calling party so as to notify that the voice call is unavailable, when the determination device determines the voice call is unavailable; and wherein the transmitter/receiver unit comprises: a notification device that notifies the state of use of the transmitter/receiver unit to the base unit when receiving the inquiry of the state of use from the base unit.