| 摘要 |
PURPOSE:To allow a backup device capable of rapidly dealing with the occurrence of a fault by using a periodic notice function using a backup line, thereby monitoring the state of the backup line and an automatic line backup device of an opposite station. CONSTITUTION:The backup device is provided with a private line fault detection section 10 detecting a fault of a private line and a line terminator, a data communication line changeover section 9 selecting a private line or a backup line for a data channel, a terminal adaptor section 12 implementing call control in an ISD network and signal conversion for data, and a communication control section 11 discriminating whether or not the communication is for the purpose of periodic notice based on outgoing subaddress information in the call control information in the ISD network, and the automatic line backup device 6 of a relevant station monitors the line state of the backup line 8 and the state of the automatic line backup device of an opposite station based on the periodic notice given at a prescribed interval period using an outgoing subaddress information area in the call control information from the automatic line backup device of the opposite station through the backup line 8 to rapidly deal with the occurrence of a fault.
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