| 摘要 |
PURPOSE:To detect a case when a communication line corresponding part on which a subscriber line is not mounted is made access and a case when the communication line corresponding part which is not connected is made access as the same fault by providing an answer signal output buffer operated when the subscriber line is mounted. CONSTITUTION:When the connector 6 of the subscriber line 7 is mounted on a connector 10, the inhibit terminal of the answer signal transmitting buffer 17 is earthed to operate the buffer 17. When a processor 1 transmits a command, the command is decided in an order decision part 14, and if the command is normal, the command is executed in an order executing part 15 and an answer signal is transmitted to the processor through the buffer 17 from an answer signal forming part 16. When the subscriber line 7 is not mounted, the buffer is inhibited and the answer signal is not transmitted to the processor 1.
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