PURPOSE: To register a malicious calling caller's number by a simple operation from a telephone set.

CONSTITUTION: At the time of judging that the incoming call from a subscriber 1B is the malicious calling as the result of a communication, a receiver presses a malicious calling button of a telephone set 10. Thus, a central processing unit 12 receives a malicious calling button input command, and transmits a malicious calling registering command setting the caller's number to a central processing unit 15 after an on-hook. The central processing unit 15 receives this command, and newly registers the caller's number set by the command in the malicious calling caller's number list of a data base 16. Afterwards, at the time of the calling of the subscriber 1B, the central processing unit 12 transmit a 'releasing' message to an ISDN network 1A, and controls the incoming call for the caller's number is registered in the data base 16.