| 摘要 |
PURPOSE:To select directly a trunk line talking and an extension talking from a manager telephone set by providing a manager access signal detecting circuit to a secretary telephone set. CONSTITUTION:When the manager telephone set 9 hooks off, a DC current detection circuit 7 inputs an output information the forming of a DC loop to the control terminal of the manager access signal detection circuit 13. The circuit 13 uses a prescribed signal generated by the telephone set 9 to control a control circuit 16 thereby activating the 2nd relay 11. As a result, the telephone set 9 is connected to the 1st line terminal via the 3rd relay 12, the circuit 7 and the relay 11 to attain talking with the trunk line.
|
