Patent ID: 7355982

Claim:
A subscriber line terminal device, connected by an optical fiber to a subscriber line terminating device, comprising: a reception unit, which receives a plurality of monitoring signals sent from said subscriber line terminating device via said optical fiber, said plurality of monitoring signals indicating normality or abnormality of a plurality of monitored items in the subscriber line terminating device respectively; and, a selection unit, which, when two or more among said plurality of monitoring signals received by said reception unit indicates abnormality, selects a monitoring signal with high order of priority from among the two or more monitoring signals indicating abnormality, based on a prescribed order of priority wherein, said plurality of monitoring signals include, a first signal, indicating normality or abnormality of a power supply of said subscriber line terminating device; a second signal, indicating normality or abnormality of a cable connecting said subscriber line terminating device and a user terminal; a third signal, indicating normality or abnormality of a reception state of optical signals of said optical fiber at said subscriber line terminating device; and a fourth signal, indicating normality or device abnormality of said subscriber line terminating device; wherein said order of priority stipulates the order of priority of said first signal and said second signal, the order of priority of said first signal and said third signal, and the order of priority of said first signal and said fourth signal.