| 摘要 |
PROBLEM TO BE SOLVED: To enable communication via a second communication network instead of a first communication network in a case that communication via the first communication network is disabled because a first communication control device of the first communication network becomes unavailable.SOLUTION: When a first communication control device 11 becomes unavailable (S3), a communication permission request signal including conditions for performing communication of a subscriber of a first communication network 1 is transmitted to a second communication control device 21 (S9-1). When a communication request is received (S23), and the communication request satisfies the conditions, that is, when a sender identifier according with a subscriber identifier within the conditions is included in the communication request, control is executed so that a communication terminal 101 that has transmitted the communication request can perform communication (S33). |
