| 摘要 |
A tone detecting circuit (16) detects the tone of local line signals, and outputs the logic duration for it. An MPU (18) outputs local line hook flash signals, and also outputs a multi frequency code in the dial digits by accessing its own number. A communication circuit (22) amplifies input signals, and outputs the amplified signals to a transceiver. A switching circuit (24) connects or disconnects the line between a rectifying circuit (12) and the communication circuit (22), and switches over the communication path in accordance with the hook flash signals of the MPU (18). The circuit searches all the telephone numbers of the other party by one touch, when the other party has a number of telephone lines.
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