PURPOSE: To improve the convenience of a call originating user by registering another personal communication number in the personal communication number of a personal communication user and informing the call originating user of the registered another personal communication number when an incoming call is made to the personal communication number.

CONSTITUTION: A personal communication user 8 registers a personal communication number PTN3 which is usable in a personal communication network 43 against a personal communication number PTN2 registered in the data base 62 of another personal communication network 42. When a call originating user 1 originates a call to the number PTN2 under such condition, an exchange node 71 discriminates the network 42 and sends the signal to an exchange node 72. The node 72 performs access to the data base 62, obtains the information regarding the number PTN3 registered against the number PTN2, and informs a terminal 21 of the information through the node 71. Upon receiving the number PTN3, the user 1 again originates the call to the number PTN3.