PURPOSE: To shorten the duration of a call and response, by transmitting the 1st office address code and the 2nd address code from the 1st office, and transmitting a response signal to the 1st office at the response of the 2nd office.

CONSTITUTION: A calling office transmits a remote address code and local address and synchronous codes at a fixed time interval. An office receiving a transmitted radio wave extracts a synchronous code from the call sign to synchronize with a signal. When the remote address code coincides with the address code at the checking of the address codes, the access status is displayed on a display device 9 to be called. Subsequently, the remote address is displayed on a remote office display device 10. The receiving office outputs a response signal corresponding to the call signal at a prescribed time slot. The calling office discriminates whether the response signal is correct or not, and when the signal is correct, stops the output of the call signal and starts normal communication.