LINE MONITORING SYSTEM AND ITS MONITORING DEVICE

摘要

PROBLEM TO BE SOLVED: To directly monitor a state on the side of a monitoring device from an exchange without requiring any condition such as the support of nib bits. SOLUTION: A line monitoring system presets to turn the signal state of a subscriber's line interface 34 on the side of a center station 3 into non-signal state or signal synchronism lost state corresponding to an abnormality or the like of subscriber's line interfaces 43 and 53 or network terminating parts 42 and 52 on the side of subscriber houses 4 and 5 between monitoring devices 32 and 33 and an exchange 31. In the case of the abnormality, it is reported to the exchange by turning the subscriber's line interface 34 into the signal state so that a subscriber's line extended from the exchange of the center station to the terminal devices 44 and 54 at the subscriber houses is monitored.