| 摘要 |
PURPOSE:To attain both telephone and security functions in the same subscriber line by connecting a sensor for security between a subscriber line T and ground and providing respectively a current detection circuit to lines R,T in a subscriber circuit. CONSTITUTION:When a sensor 18 detects a fault and is operated while a telephone set 16 is not in use, a ground level is fed to a current detection circuit 22 through the subscriber line T26. A terminal control section 24 discriminates a current flowing to the subscriber T line only by using a signal from current detection circuits 22, 23 and informs the result to a common control section 14 through a control line 25. The control section 14 receives the information to detect that the sensor connected to the subscriber 20 is activated, sends a display data to a display section 15 for the notice of fault occurrence. |
