| 摘要 |
PURPOSE:To connect a communication circuit between desired terminals at the calling and called subscriber sides with a low charging rate and easy handling and with no change of an existing telephone exchange network, just by providing a network adding device and a subscriber's private adding device in response to the subscriber lines in case plural terminals are connected to a pair of subscriber lines. CONSTITUTION:A network adding device AOU2 is provided with an answer circuit 21, network signal transmission/reception circuit 22, answer detecting circuit 23, extension selecting number urge signal transmission circuit 24, intra-sound band code signal reception circuit 25 and a control circuit 26. While a subscriber's private adding device ASU4 is provided with a signal transmission/reception circuit 21, start detecting circuit 42, control circuit 43 and a switching circuit 44. The AOU2 is started by a call given from a transmitter side 7, and an extension selecting number urge signal is transmitted to the side 7 from the circuit 24. When a terminal selecting signal is sent to the circuit 25 from the side 7, the circuit 26 informs a terminal 5 or 6 to the circuit 43 by the corresponding signals. Then the circuit 43 starts a designated terminal. The answer of this terminal is sent to the circuit 26. Then a circuit is closed between the side 7 and the terminal selected by the side 7. |
