| 摘要 |
PURPOSE:To test the normality of a subscriber line from an overall service digital control network terminal side by providing a loopback path on an exchange, sending a test data pattern and comparing the sent pattern with the reception pattern. CONSTITUTION:An incorporation servic digital control network(ISDN) terminal(IST)1 is connected to an ISDN subscriber line test equipment 6 via an information receptacle 7. A path between a loopback trunk 13 of a digital exchange and a digital line 11 in the equipment 6 is set based on a signal sent from a B-channel interface section (DPG/C)3 by the key entry of a signal input/display section 14. In sending a test pattern from the DPG/3 by the equipment 6 succeedingly, a test data pattern is returned to the equipment 6 via a set loop bus. The DPG/C3 receives it and collates the coincidence between the transmission pattern and the reception pattern. A control section 5 displays the result of collation on a display section 14. Thus, the normality of the subscriber line is tested.
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