| 摘要 |
PURPOSE:To simplify a circuit constitution by controlling the connection/disconnection of cross point switches in accordance with the disconnection period of a signal tone to be sent. CONSTITUTION:A link (l) is directly coupled with a sound source OSC and the cross point switches P1-P3 are arranged on the cross points between respective telephone sets ST1-ST3 and communication lines t1-t3. A control part CN controls these switches P1-P3 so as to repeat the disconnection of the switches P1-P3 in accordance with the disconnection period of the signal tone to be sent. When a signal tone A is to be sent to a telephone set ST1, the point P1 is repeatedly closed for a time T1 and opened for a time T2. In said constitution, the number of signal tone sending rinks and the number of signal tone sending cross point switches are extremely reduced and a disconnector for the signal tones is not required, so that the circuit constitution is simplified. |
