| 摘要 |
PURPOSE:To attain the test at actual operating state by connecting PCM code converters of a caller side and a called party side in series via a time division highway switch circuit to a channel link. CONSTITUTION:The PCM code converters COA, COB provided to respestive subscriber circuits LC-A and LC-B of the calling party side A and the called party side B are provided respectively with reflecting circuits 23, 30. When a telephone set 26 of the calling party side dials a telephone set 33 of the called party side, the converters COA, COB, the circuits 23, 30 and the telephone sets 26, 33 are connected in series mutually via the PCM time division highway switch circuit SW. Then a prescribed test signal is transmitted from a test trunk circuit TST to the converters COA, COB via the circuits 23, 30 and the circuit TST detects signal returned to the circuit TST from the converters COA, COB via the circuit SW. |
