Abstract: A user calls a specific number of an authentication center (member authentication device) from a mobile terminal in a state of caller line identity presentation and hangs up the mobile terminal after one ring. The authentication center can recognize the number of the mobile terminal of the caller in spite of the hang-up of the call as long as the phone number of the caller is presented during the ring. The member authentication device searches a database in the authentication center to compare the caller's number on the mobile terminal with the member registered caller's numbers for verification. Member authentication is thus executed and its result is outputted.

Abstract: The present invention enables the flexible cooperation of an internal network with an external network while preventing a direct intrusion to the internal network by physical means with respect to the access from the external network.