| 摘要 |
The system includes a device (1) for detecting hung up/picked up line, which provides a signal showing whether the line is open or closed, a device (2) f or closing or opening the line (7), which provides the data to be transmitted, a device (3) for detecting a conventional call, a module (4) for exterior connection, a power supply circuit (5), which receives electrical current fr om the telephone line (7) itself and control means (6) which, on receiving a signal through the connection module (4), transmit an appropriate signal to the device (2) for closing and opening the line (7), which transmits the dat a of a message to be transmitted.
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