When a large-scale disaster such as a large earthquake occurs, in addition to a governmental agency and a disaster prevention agency which are engaged in a recovery activity, many users use voice calls to confirm safety in a disaster area. During this time, a large volume of traffic is processed by a network, compared to a normal time. Due to the processing of the large volume of traffic by the network, it becomes a state where it is difficult to establish communication connections. Since it becomes a state in which it is difficult to establish communication connections, the traffic may be controlled by the network by regulating the communications. When the traffic is controlled by the network, it becomes difficult to make confirmation of the safety in the disaster area.
A technique has been known such that, even if a system of a mobile switching center is down or a transmission line failure occurs, and communication with a radio base station controller is disabled, a terminal of a police station or a fire station can be contacted when a disaster occurs (cf. Patent Document 1, for example).
Further, a technique has been known such that, in processing of communication requests during a time of disaster, an overcrowded condition or a congestion state is avoided as much as possible, thereby allowing as many users as possible to communicate (cf. Patent Document 2, for example).
USPTO Backgrounds
USPTO Backgrounds