Mobile communication system, IP-PBX and call holding method at the time of out-of-service mobile used for them

摘要

PPROBLEM TO BE SOLVED: To provide a mobile communication system capable of continuing a call between terminals even if an inter-terminal communication route is changed. PSOLUTION: Even if a dual terminal 22 performing radio communication in an IP network 100 gets out of the range of the IP network 100, IP-PBX 10 performs transmission to the dual terminal 22 via a PSTN network 200 so as to allow the dual terminal 22 to discriminate whether an incoming call from the PSTN network 200 is a general incoming call from the PSTN network 200 or an incoming call which requires to continue an in-range call from the IP-PBX 10. In the case of continuing the in-range call, a path of the dual terminal 22 and an IP terminal 21 is replaced to use the PSTN network 200. Consequently, the call between the IP terminal 21 and the dual terminal 22 is automatically held without allowing a user to be conscious of the change of the communication route. PCOPYRIGHT: (C)2008,JPO&INPIT