| 摘要 |
PURPOSE:To report a center fault surely in a short time, by starting a transmitting circuit after detecting the receiving state of a terminal equipment by the change of a CD signal line from turn-on to turn-off. CONSTITUTION:A CD detecting circuit is provided to detect a carrier detection signal from an MODEM, and an ER control circuit is provided to control the transmission of a terminal equipment ready signal, and a transmitting circuit is provided to not only control various signal lines but also transmit a center fault report signal. The ER control circuit turns on always a terminal equipment ready signal line ER at a no-communication time. A call signal is transmitted from the other-party terminal following the incoming from the other-party terminal; and when this call signal is terminated, the carrier detection signal is changed from turn-on to turn- off, and the CD detecting circuit detects this state to start the transmitting circuit. |
