GB112650A - Improvements in Automatic Telephone Systems. - Google Patents

Abstract

112,650. Relay Automatic Telephone Co., and Johnson, B. B. Jan. 15, 1917. Exchange systems.-The character of a line that is faulty is automatically changed so that when called it switches the calling line to another line, which may be that of an exchange attendant. If the faulty line is called by an operator offering a preferred call, an out-of-order tone may be given to the operator. When a line S becomes faulty, its line relay L is energized and causes one of the switching-relays C1, C2 to connect it to an idle junction line, as described in Specification 9840/14, the relay, C2 say, looking up in a circuit 5 including the cut-off relay CO and an additional relay F. The impulse relay IR of the selected junction is energized over the faulty line, and, after an interval determined by a timing- device TS, opens circuit 5. The relay F, being slow to de-energize, locks up over a circuit 6 including the faulty line, but the cut-off relay CO is de-energized. In a normal call, a set of selecting-impulses quickly follows the extension of the line to the relay IR, and a relay R is arranged to open-circuit the timing-device TS and to extend the circuit 5 to the next digit stage. When a line S in normal condition is called, one of the relays C1, C2, &c. is energized over circuit 7 and locks up in known manner over circuits 5 including relays CO and F. When a faulty line is called, (its relay F being energized), the circuit 7 is extended over branch 10 to the relays CL, CLI &c. of the attendant's circuit O, to which the calling-line is connected. If this attendant's line is busy, the relays F2, CO2 will be energized and the circuit 10 will be extended over lead 13 to an attendant's auxiliary line. An operator handling a preferred call makes connexion to the junction P and can release a local connexion by earthing the lead 51. If the wanted line is faulty, an out-of-order signal is given over circuit 14 to the operator. If the junction P ends in a jack at the operator's position, the circuit 14 may be connected over circuit 51 to the bush of the jack.