Abstract: A switching arrangement that can be connected in a communications channel that comprises a pair of lines between sets of terminal equipment, which comprises: (i) a series switch (1,2) for connection in each of the lines; (ii) a shunt switch for connection between the lines; and (iii) a control circuit (5) that can actuate the series switches (1,2) and can actuate the shunt switch on receipt of a signal sent along the channel: wherein the control circuit (5) can actuate the shunt switch and the series switches (1,2) on receipt of one or more signals but the shunt switch will remain closed over a different time period than that during which the series switches remain open, in order to allow different tests to be performed on the channel, and wherein one or more of the switches comprises a solid state switch.

Abstract: A maintenance termination unit (MTU) for use in telephone circuits. The MTU comprises a switching arrangement which can be connected in a communications channel, the communications channel comprising a pair of lines. The switching arrangement is connected between a set of exchange-side terminal equipment and a set of subscriber-side terminal equipment. The arrangement comprises first and second line switches, each of which is series connected in one of the lines. Each line switch comprises a control terminal, and has a closed state in which it will pass normal line current, and an open state in which it will pass at most a reduced line current. The arrangement also comprises a control circuit which is connected to the channel between the line switches and the subscriber-side terminal equipment.