PURPOSE: To attain detailed reply depending on each caller by sending a different message from each caller, that is, each caller number while a call comes to the telephone set in the automatic answering mode.

CONSTITUTION: Caller number information in call information received by an ISDN interface section 2 is sent to a CPU 3. The CPU 3 starts a transmission message selection section 4 to offer caller number information. The transmission message selection section 4 accesses a message registration memory 5 to read all caller numbers in an address section 5a and to compare them sequentially with caller numbers sent from the CPU 3. When a coincident number is detected, a message corresponding to the caller number is read. The message read from the message registration memory 5 is sent to the ISDN interface section 2.