COMMUNICATION TERMINAL APPARATUS AND CONTROL METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a communication terminal apparatus which can switch, without fail, without casing instantaneous cut-off state of a circuit, when switching from the communication terminal apparatus to a telephone set connected to the communication terminal apparatus. SOLUTION: The communication terminal apparatus is provided with an external telephone set connection unit connecting to a communication device; a circuit switching unit which changes over a seizure state of a communication circuit from the communication terminal apparatus to the communication device; a circuit voltage detection unit which detects a circuit voltage of the seizure state of the communication circuit; a circuit DC voltage holding unit which holds the circuit voltage constant, when switching the seizure state of the communication circuit from the communication terminal apparatus to the communication device; a circuit voltage control unit which controls the circuit DC voltage holding unit; and a holding means which holds the circuit voltage constant, by connecting the communication terminal apparatus and the communication device in parallel to the communication circuit, when switching from a state that the communication terminal apparatus is seizing the circuit to the communication device. COPYRIGHT: (C)2010,JPO&INPIT