Patent ID: 8170201

Claim:
An improved LAN having terminals connected to a line concentrator via signal lines for carrying signals between the terminals and the line concentrator, wherein the improvement comprises: power feed lines connected to the terminals; and a power feeding system that includes a power feed section for selectively feeding power to the power feed lines, a current monitor section for detecting whether current is flowing to each terminal and, if so, whether the current has a value within a preset current range which indicates that the respective terminal receiving the current is a telephone terminal, a control section for controlling the power feed section to stop feeding power to particular terminals if the current monitor section detects that each current flowing to those terminals has a value that is outside the preset current value range, and to continue feeding current to particular terminals if the current monitor section detects that each current flowing to those terminals has a value within the preset current range, and a line state monitor table for storing given states of the power feed lines and the signal lines, wherein the control section controls operation of the power feeding system based on the line state monitor table.