| 摘要 |
PURPOSE:To control a terminal equipment connected via an extension freely by sending a dial signal in response to a selector switch at an external line calling and sending a PB signal independently of the state of the selector switch at the extension call, trunk line. CONSTITUTION:When a trunk line key of an operation key section 1 is operated and a dial key is operated, a control circuit 4 sends a high level switching signal to a PB signal switching port of a dial IC2, the dial IC converts the signal into a DP signal accordingly and the DP signal is sent via a channel circuit 6 and an external channel 8. On the other hand, the extension key of an operation key section 1 is operated and when the dial key is operated, a control circuit 4 switches a relay contact 5 to the position of the extension channel 9 and a low level switching signal is sent to the Pb signal switching port of the dial IC2. Thus, the dial IC is converted into the Pb signal and the Pb signal is sent via the channel circuit 6 and the extension channel 9.
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