Patent ID: 6847718

Claim:
A method for feeding power to a subscriber-side network termination device connected to a central office-side line termination device through a subscriber line, wherein the subscriber-side network termination device is normally powered by a commercial power source, comprising the steps of: at the subscriber-side network termination device, extracting DC power using a power extractor from the subscriber line to supply it to circuits in the subscriber-side network termination device; determining whether a commercial power failure occurs; controlling a network termination circuit and the power extractor such that, when the commercial power failure occurs, the power extractor extracts the DC power from the subscriber line, the network termination circuit transmits a power failure signal to the central office-side line termination device by using a signaling bit and, when the commercial power source is restored, the network termination circuit transmits a power restoration signal to the central office-side line termination device by using a signaling bit; at the central office-side line termination device, feeding the DC power into the subscriber line using a remote power feeding circuit; controlling a line termination circuit and the remote power feeding circuit such that, when the power failure signal is received from the subscriber-side network termination device, the remote power feeding circuit starts the DC power feeding to the subscriber-side network termination device via the subscriber line and, when the power restoration signal is received from the subscriber-side network termination device, the remote power feeding circuit stops the DC power feeding to the subscriber-side network termination device via the subscriber line.