Patent ID: 8107615
Filing Date: 2012-01-31
Classification: H04M

Abstract:
1. A method for checking the function for inverting the polarity on a subscriber line, including a plurality of wires, for connecting at least one subscriber to a subscriber line module which has at least one inversion device and a current measuring device associated with the inversion device comprising: isolating the subscriber line at least partially from the deactivated inversion device; inverting the polarity on the subscriber line using a connected direct current source; using the current measuring device to ascertain a first item of information representing the present direction of current flow on the subscriber line; activating the inversion device; using the current measuring device to ascertain a second item of information representing the present direction of current flow on the subscriber line; isolating the direct current source from the subscriber line; connecting the subscriber line to the activated inversion device; using the current measuring device to ascertain a third item of information representing the present direction of current flow on the subscriber line; and using the ascertained first, second and third items of information to check that the inversion is functioning.