PURPOSE: To improve operability in speech transfer by calling an opponent by automatically dialing a telephone number obtained by requesting the transmission of the telephone number of a transfer destination by a remote control switch by using an optical signal of infrared ray, etc.

CONSTITUTION: A signal from the transmission part 14 of a data transmission/reception part 11 is transmitted by converting to the optical signal by a light emitting part 16. For example, when it is requested to transfer speech from a telephone set A to a telephone set C while the speech is being held between the telephone set A and a telephone set B, a prescribed remote control switch is depressed directing the light emitting part 16 to the telephone set C. The optical signal to request the transmission of the telephone number of the telephone set C from the transmission/reception part 11 is transmitted from the light emitting part 16. The signal is received by the telephone set C, and the telephone set C converts its own telephone number to the optical signal, and transmits it to the telephone set A. A light receiving part 17 receives it, and transfers it to a demodulation part 13 via a reception part 15, then, it is received and confirmed by the transmission/reception part 11. The telephone number is automatically dialed from a control part 9, and is sent out to the telephone set C, then, it is called, and the speech between the telephone set A and the telephone set C can be performed.