| 摘要 |
PURPOSE:To facilitate usage by connecting a circuit through an automatic incoming circuit when a call signal is detected, calling a telephone set at the reception side after a private call becomes possible and holding a receiver at the transmission side in the called state until a telephone set is hooked off by the transmission side. CONSTITUTION:When the call signal is transmitted, a call signal detecting circuit 12 detects said signal, which is given to a control circuit 10. When a switch S3 is turned on, a circuit is connected between transmission and reception sides, thereby attaining communications between private telephone set. In this state, said sets execute the synchronous operation, and a private call synchronizing signal is given to the control circuit 10 at the point when synchronization is established between transmission and reception sides. When the private call synchronization is established, the transmission side is brought into an opposite party off-hook standby, while at the reception side the control circuit 10 turns on a switch S2 and indicates a call signal generator 15 to generate the call signal. When a listener picks up a receiver in said state, the hook-off is detected by a self-station hook-off detecting circuit 13 at the reception side. Thus the automatic instantaneous call communications network including the private call can be used at the same convenience as an automatic instantaneous call communications network.
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