COMMUNICATION RELAY METHOD, COMMUNICATION RELAY PROGRAM AND COMMUNICATION RELAY APPARATUS

摘要

Mobile dual terminals incorporating both WLAN and PHS functions disable the WLAN function, in terms of power saving, as long as they are in a PHS zone and even if they are in a WLAN zone. Accordingly, if such a mobile dual terminal receives a telephone call, it is normally called up by an S-P gateway (104) via a PSTN, with the result that there disadvantageously occurs a charge to the caller for the telephone call. In view of this, according to the present invention, a call from an S-P gateway (104) to a receiving terminal (102) (dual terminal) is disconnected before the occurrence of a charge for the call, while the receiving terminal (102)is caused to call back to the S-P gateway (104) via an IP network or via a PSTN. Then, a SIP server (100), instead of the receiving terminal (102), is caused to determine a calling terminal (101) that is the destination of the call back, whereby the telephone call from the receiving terminal (102) is connected to the calling terminal (101). The present invention has proposed four systems, which include "Reconnection System", "Reconnection Plus Recall System" and "Recall System" in addition to the "Call Back System".