Patent ID: 6728347
Filing Date: 2004-04-27
Classification: H04Q

Abstract:
A network station (1) comprising a selector switch (4) for coupling a switching center (2) to a POTS or ISDN telephone, a detection circuit (3) which, after being put into operation or after a mode change from the POTS mode to the ISDN mode, is provided for coupling the switching center (2) to an ISDN network terminator (11) and, in the event of a mode change from the ISDN mode to the POTS mode, for coupling the switching center (2) to the POTS telephone by actuation of the selector switch (4),wherein the detection circuit (3) comprises a rectifier (13) coupled to the input terminals (5,6) of the selector switch (4), a threshold detector (14), a first and second pulse shaper circuit (16, 17) and a bistable relay (18), in that the threshold detector (14) is provided for comparing the signal produced by the rectifier (13) to a threshold value and the first pulse shaper circuit (16) is provided for generating an actuation signal for the bistable relay (18) to change the selector switch (4) from the POTS mode to the ISDN mode when the signal generated by the rectifier (13) reaches the threshold value, and in that the second pulse shaper circuit (17) is provided for generating an actuation signal for the bistable relay (18) to change the selector switch (4) from the ISDN mode to the POTS mode when the ISDN network terminator (11) cannot carry out an ISDN operation with the switching center (2).