| 摘要 |
PURPOSE:To enable customary units to be used in common by so controlling a channel switch at reception, and connecting to an interface for sole telephone set to obtain a response, and a dial signal is identified by a PB receiver to control the channel switch. CONSTITUTION:Reception from extensions L1, L2 are sensed through a reception detecting circuit 1 by a main CPU 4. Under control of a sub CPU 24, the channel switch 21 of an interface unit 20 for accommodating the sole telephone is turned on to make an automatic response. The unit 20 sends out dial tone to the telephone line by a sound source 22 to inform the partner of the line connection being made. When the caller at the telephone line sends out the dial corresponding to the extension number, it is identified by the PB receiver 23 and makes a call to the extension by the CPUs 4, 24 to turn the channel switch on.
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