| 摘要 |
PURPOSE:To enable to perform the sectioning test of the network control unit from the telephone station side, by sectioning the terminal unit from the subscribing telephone line to form the internal folding loop with the test signal from the telephone station. CONSTITUTION:When the signal fed from the telephone station 10 via the subscriber telephone line 20 is the terminal callout signal, it is detected at the terminal callout signal detection circuits 421, 422. Further, the switch circuits 43, 44 are controlled with this detection and the corresponding terminal units 501, 502 are connected to the subscriber telephone line 20. Further, when the test signal is fed, it is detected at the test signal detection circuit 423. The switch circuit 451 is controlled with this detection and the terminal units 501, 502 are sectioned from the subscriber telephone line 20 to form the internal folding loop via the resistor 452 and diodes 453, 454. |
