Circuit arrangement for the transmission of communication signals

Claim 1

In a circuit arrangement for the transmission of intelligence signals between a central office and two subscribers who are connected over a common subscriber line to the central office, wherein the intelligence signals are transmitted from the central office over the subscriber line in digital form to a conversion device in which incoming digital signals are converted into analog signals and vice versa, and wherein the conversion device is connected to the two subscribers by cables; the improvement comprising a first switch connected to the subscriber line; a second switch connected to a cable of one of the subscribers, said first and said second switches being operatively coupled to each other; a bypass line electrically connecting said first switch to said second switch; a measuring device which detects a dc voltage present on the subscriber line, said measuring device being connected to the subscriber line between the central office and said first switch, said measuring device being electrically connected to said first and said second switches for operating each of said switches; and wherein said measurement device responds to a voltage which is less than a predetermined value by operating each of said switches to connect the bypass line to the subscriber line and to the cable of one subscriber while disconnecting said conversion device; and said measuring device responds to a voltage which exceeds a predetermined voltage by operating each of said switches to connect said conversion device to the subscriber line and to the cable of said subscriber while disconnecting said bypass line.