PURPOSE: To prevent a fault arising at a receiver in an emergency mode, etc. by driving a sound output device to inform the originating side that the dialing is wrong in case the originating side has the wrong dialing with a receiver exclusive for reception of data from a specific device.

CONSTITUTION: A network controller NCU2 detects the presence or absence of an incoming call, then closes a telephone circuit if an incoming call is detected to wait for the prescribed data to be fed from a specific device like an informing device, etc. Then the NCU2 decides that the originating side is equal to a specific device when the prescribed data is received by a data receiver 1. A CPU4 has the prescribed processing based on the received data and sends the data to an output device 6. Then the device 6 delivers the processing data and opens the telephone circuit. While it is decided that the originating side is equal to a human being not a specific device in case it is impossible to receive the prescribed data within a fixed period of time after the telephone circuit is closed. Thus a sound output device 8 informs in voices via the telephone circuit L that the dialing is wrong.