Abstract: In a self-routing switch which comprises a plurality of switching stages inserted between pluralities of input and output lines and cascade-connected by pluralities of input and output links, each switching stage includes a plurality of cascade-connected store/switch elements. Each store/switch element of each switching stage outputs an information data input thereto from the corresponding input link to the corresponding output link or shifts the input information data through a predetermined number of cascade-connected elements and outputs it to the corresponding output link, in accordance with a portion of routing information contained in the input information data, which portion corresponds to the switching stage.

Abstract: This invention relates to a current supplying circuit for supplying a current to a terminal apparatus through a ring line and a tip line which are connected through resistance elements to a potential source and ground, respectively. This current supplying circuit includes respective detectors for generating first and second detection signals of amplitudes proportional to the currents flowing in the ring and tip lines, respectively, a circuit for generating a reference signal, and a comparator for comparing the signal difference between the first and second detection signals and the reference signal so as to produce a signal in accordance with the compared result, thus a shorted-to-ground fault on the ring line or tip line being detected by monitoring the signal produced in accordance with the compared result. After the shorted-to-ground fault is detected, the current supplying circuit is protected from breakdown.