Patent ID: 7577135

Claim:
An IP telephone system configured by a main control device for controlling the entire operation of an IP exchange; said IP exchange storing a plurality of IP terminals for each lodgment through a circuit by a control of said main control device and comprising a plurality of signal control devices performing a call control; said circuit for connecting between said IP exchange and said lodgment; a backup exchange installed in said lodgment for detecting a trouble of said IP exchange or a fault of said circuit and backing up said lodgment; and said plurality of lodgments comprising said plurality of IP terminals, said IP telephone system performing a centralized control and operation of all the IP terminals by the IP exchange, wherein said backup exchange performs an access confirmation with said IP exchange, and in a case in which the access confirmation cannot be secured from said IP exchange, determines it as an occurrence of a fault of said IP exchange or a failure of said circuit, and switches over from a waiting state to an operating state; said IP exchange performs an access confirmation with said IP terminals installed in said plurality of lodgments; said plurality of IP terminals, in a case in which a life check based on the access confirmation from said IP exchange cannot be received, log in to said backup exchange after logging out from said IP exchange; said backup exchange performs communication control of said IP terminal which is logged in said backup exchange.