Patent GB-303086-A (GB)
Title: Improvements in and relating to automatic or semi-automatic telephone systems
IPC: H04M3/60
Filed: 1927-09-27
Abstract: 303,086. Dicker, S. G. S., (Associated Telephone & Telegraph Co.). Sept. 27, 1927. Automatic and semi-automatic exchange systems. - Toll calls to an automatic exchange are set up over junctions associated, at the same end of the junctions as the toll board, with dialling operators' positions, the connections being transferred to, the toll board after operation of the switches, to enable called subscribers to be signalled from the toll board. Two methods are described. In the first, Fig. 1, the dialling operator receives the wanted number over an order wire from the toll operator and plugs into jack J of a junction 2, 3 extending to the desired exchange, the junction being provided with equipment TC accessible at jack J1 at the toll board. The dialling operator informs the toll operator of the junction selected and dials the number, after which she withdraws plug P. In the second method, Fig. 2, the toll operator plugs into jack J2 of a trunk 102, 103 leading to a dialling operator's position and gives her the necessary information. Dialling operator then plugs into pack J3 of a junction to the desired exchange, throws key K1 and dials the number. On restoration of K1 the toll operator has control of the connection with the exception of release which is effected by the withdrawal of plug P3 by the dialling operator. First method, Fig. 1. Dialling operator inserts plug P of her sending equipment DC into jack J to complete a circuit over ring contacts of P, J for relay 50 (upper) which at 52 completes a circuit for 60, 45, 30, 10 in series, 45 remaining inoperative. Relay 65 pulls up over 63, locks over 68, 76, switches through at 66, 69 and completes a locking circuit for 50 and 71. Relay 30 opens the leads to the toll board at 31, 34 and energizes relay 35 which locks over 38, prepares a bridge across the junction at 36, and at 39 completes a circuit for 60 independent of dialling operator's circuit DC. Dialling operator now sends the wanted number and withdraws plug P, the leads to the toll board being closed on the relapse of relay 30. It is assumed that the toll operator has previously plugged into pack J1 of the assigned junction so that relays 22. 40 are operated in series with 60 (lower). Relay 40 opens the holding circuit of 35 which, on relapse, opens the bridge at 36, and at 39 opens a previously traced circuit of 60 which however holds in series with 22, 40. The connection is now under complete control of the toll operator who rings the wanted subscriber. On removal of plug P1 to release the connection, relays 22, 40, 60 fall back and relay 75 is bridged across the junction. Relay 75 release relays 50, 65 and then falls back. Toll operator fails to insert plug; release by dialling operator. Relay 35 does not release when dialling operator removes plug P so that the connection is held over bridge R1, 36, and lamp L is flashed by interrupter I. Dialling operator converses with the toll operator over the order wire and if the toll operator does not then want the connection, dialling operator brings about release by re-inserting plug P and throwing key K to the right. The bridge R1, 36 and the loop in operator's circuit DC are thus opened to release the connection, and direct battery over K increases the current over relay 45 sufficiently for it to operate and open the holding circuit of 35. Removal of plug P with key K still thrown to right releases 30 which is followed by 35, 45 and 60 whereupon the remaining relays of TC restore as previously described. Wrong number dialled. Dialling operator may release the operated switches by throwing key K to the left thereby opening the loop without affecting the relays of TO. Second method, Fig. 2. Toll operator inserts plug P2 into jack J2 of an idle trunk 102, 103 leading to dialling operators position, sleeve relay 122 pulls up and relay 120 bridged across her cord circuit 01 is energized in series with relay 145 at dialling operator's position so that lamps L2 and L3 at both positions are lit. Dialling operator throws key K1 to listening position (left) energizing relay 140 which disconnects relay 145, this relay being however held over its lower winding. Relay 120 falls back and' extinguishes L2 to signal toll operator who informs dialling operator of the wanted number. Dialling operator inserts plug P3 into jack J3 of an idle junction 112, 113 leading to the desired exchange, throws key K1 to right and dials the wanted number, the spealiing circuit being closed at 156 by sleeve relay 155. Relay 155 also prepares at 158 the circuit of ring- ing relay 150 and extinguishes lamp L3 at 159. During dialling, 140 is held over 146 as well as over 158, 136. Dialling operator then returns K1 to normal. If the wanted line is busy, polarized relay 135 is operated intermittently and intermittently releases 150 which results in intermittent operation of 120 to flash lamp L2. If wanted line is free, relay 135 pulls up, 140 remain side-energized and lamp L2 glows steadily. Toll operator then applies ringing current over key K3 to operate AC relay 130 which at 131 completes the circuit for ringing relay 150 in series with 140. Reversal of current when called subscriber replies de-energizes 135 and 140 again operates to disconnect 145 and extinguish lamp L2. When called subscriber hangs up, lamp L2 lights up, toll operator removes plug P2, and dialling operator's lamp L3 lights up over 159, 147 to inform her she may remove plug P3 to release the connection.