| 摘要 |
In a communication network system (10) having a concentrating interval (250) of the number of communication lines smaller than the number of subscriber terminals (400) at intermediate positions in communication lines which connect a plurality of subscriber lines and a Public Switched Telephone Network (PSTN) (1000), when an emergency call is generated from a certain subscriber terminal to, for example, a fire-police (500), the line which has performed the emergency call communication in a concentrating interval is held for a predetermined time after the emergency call communication was disconnected. When a re-alerting signal (701) is generated from the fire-police to the subscriber terminal within a predetermined time, a call signal (901) is transmitted to the subscriber terminal through the line held in the concentrating interval. Even when an origination signal (904) is generated from the subscriber terminal to the fire-police within a predetermined time, an origination signal (704) is transmitted to the fire-police through the line held in the concentrating interval. A management table (225) is used for holding the line in the concentrating interval. <IMAGE> |
