PROCEDURE FOR QUICKLY TESTING THE SERVICEABILITY OF A SUBSCRIBER CIRCUIT

摘要

The invention relates to a subscriber circuit of a digital telephone exchange with connectable subscriber lines (TL), said subscriber circuit consisting of a high-threshold part (HV) and a low threshold part (NV) containing a signal processor. According to the invention, test functions for testing the reliability performance of the subscriber circuit are integrated into the same using existing components and without placing a significant burden on the signal processor. The injection of an alternating current (S) produced by a tone generator (TOG) is followed by a frequency selective current threshold comparison by which means the reliability performance of the subscriber circuit can be determined rapidly.