Patent ID: 6490342
Filing Date: 2002-12-03
Classification: H04M

Abstract:
A method for quickly testing an operability of a subscriber circuit of a digital telephone exchange, the method which comprises:producing, with a tone generator provided in a subscriber circuit, an alternating voltage having a given frequency; amplifying the alternating voltage with an amplifier provided in the subscriber circuit for supplying an amplified alternating voltage; feeding the amplified alternating voltage into connecting paths of the subscriber circuit, the connecting paths being provided for a connection to respective lines of a subscriber line; diverting the amplified alternating voltage to ground via respective capacitors connected to the connecting paths for the respective lines; measuring respective alternating current levels in the connecting paths for providing respective measured alternating current levels; forming a sum of the respective measured alternating current levels for providing a summed alternating current level; comparing, in a frequency-selective manner, the summed alternating current level with a current threshold value; and selectively outputting a positive test result, if the summed alternating current level exceeds the current threshold value, and confirming a defect, if the summed alternating current level is below the current threshold value.