| 摘要 |
PURPOSE:To detect the call-out or end of call of the digital terminal by the subscriber line in base band multiplication through the addition of the relay circuit to the subscriber circuit of the cross-bar exchanger. CONSTITUTION:When the telephone set is hooked off, the relay L of the telephone subscriber circuit 8 is operated, ground is detected at the subscriber identifying terminal IT, and the winding S1 in delay restoration operation of the relay S of the subscriber circuit for digital terminal 9 is operated to close the contact S. The relay L of the circuit 9 is operated to inform the call-out to the common control unit of the exchanger, and connection is made to the trunk to which the digital terminal monitor unit 13 is connected. Thus, the communication lines A and B and control line C are terminated with the unit 13 to detect the true call-out from the digital terminal. When a call-out is present, the trunk is controlled to deliver ground to the line C and the contact s is kept holding with the power application to the winding S2. |
