| 摘要 |
PURPOSE:To make the selective call of a specific other party possible even in a line having branches by detecting an audio frequency signal, which corresponds to a closed contact of an address designating switch, from a data communication line. CONSTITUTION:When a terminal A is used as a host to call a terminal C, a push-button switch 4c of an adapter QA is depressed. Then, the signal having a corresponding audio frequency is transmitted from a signal transmitting circuit 1 and is detected and outputted by a signal receiving circuit 7 of the terminal C through a data communication line K. Since address designating switches 8c are not closed in terminals A, B, D, and E other than the terminal C, this audio frequency signal is not detected there. In this state, relay windings 5 of terminals A and C are charged, and call circuits 9 of both terminals are connected mutually. When the call is terminated, the self-holding state of a relay contact 2 is released. |
