An echo canceler includes a summing device that subtracts a correction signal from a received signal, the difference of which represents the far-end signal with an error component. The connector includes an inner peripheral portion to be welded to one battery, and an outer peripheral portion, provided outside the inner peripheral portion, to be welded to the other battery. Therefore, a temporary release mode is set to temporarily prohibit the identification information reading processing. A communication control section references the contract service information and the maximum number of sessions in the origination filter table based on the originator identifier in the message received from a communication terminal, determines whether or not the service indicated by service type information in the message can be used, and determines whether or not a new session can be established.