off hook circuit

基本解释

The automatic two-way signaling used on these circuits causes the station instrument on one end of the circuit to ring when the station instrument on the other end goes off-hook.
这些线路上使用的自动双向信令引起线路一端的电话机振铃，而另一端的电话机摘机应答。
By the method, when the telephone has a long time without conversation, and the hook switch circuit is in off-hook state, the switch circuit can be changed into on-hook state automatically.
藉由此自动挂机的方法，当电话系统在持续一预设时间未进行正常通话的时候，且叉簧电路为摘机状态时，叉簧电路仍可自动切换成挂机状态。
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