To detect mis-connection of a 4-wire line, in which detection accuracy of the mis-connection by testing the presence of mis-connection of each line of the 4-wire line and to execute the detection of mis-connection of the 4-wire line that is executed, even when a subscriber is absent.
A test master station 200 is in branch-connection to a station side of a 4-wire line 100, a test slave station 300 is in branch-connection to a subscriber side of the 4-wire line 100, and the test master station 200 uses two optional lines to apply 1st feeding to the test slave station 300. The test slave station 300 receiving power sends a specific identification to a test master station 200 through each of lines not used for feeding, and the test master station 200 compares the received identification signal with an identification signal, corresponding to the received line to detect a mis-connection.
KUGISAKI TETSUYA
KACHI SUMIO
FURUKAWA ELECTRIC CO LTD
Next Patent: METHOD AND SYSTEM FOR STARTING CONTRACTED SERVICE FOR ELECTRONIC EXCHANGE