Function testing method for ISDN lines e.g. used for transmission of intruder alarm signals, has tested terminal called via test service identification which differs from terminal service identification

摘要

The testing method selects a tested terminal (1) and determines its call number (123) and service identification (T), with subsequent selection of a different test service identification (P) for calling the tested terminal via the D-channel of the ISDN line, the corresponding response signal (AS) evaluated. The ISDN line function is verified when the evaluation indicates that the number is correct but the service is not available, a line fault indicated when the number cannot be reached.