Communication control apparatus and radio communications system

A radio communications system which allows a plurality of subscriber terminals to communicate with each other via radio base stations by employing a communication controller coupled to the radio base stations for managing locations of the subscriber terminals and controlling incoming and outgoing calls to/from the subscriber terminals, the radio communications system comprising:

• means activated upon predetermined conditions for transmitting a response request signal from the communication controller to a specific subscriber terminal by using a radio link via one of the radio base stations which covers an area where the specific subscriber terminal is located, said response request signal containing an identification code of the specific subscriber terminal;
• means for transmitting a response signal, in reply to the response request signal, from the subscriber terminal having the same identification code as that contained in the response request signal to the communication controller via the one of the radio base stations;
• and
• means for recognizing the presence of an unauthorized subscriber terminal having the same identification code as the specific subscriber terminal's identification code, if a plurality of response signals have been returned in reply to the response request signal intended for the specific subscriber terminal.