Patent GB-283853-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1928-01-07
Abstract: 283,853. Associated Telephone & Telegraph Co., (Assignees of Crocker, T. F.). Jan. 17, 1927, [Convention date]. Semi-automatic and manual exchange coinfreed systems.-A toll-recording and pay station operator is provided with a set of keys common to all the cords at her position and associated with a particular one by its speaking key. By means of the keys she can dial, collect and refund coins, &c. over either end of the cord. A toll operator has similar position equipment. Further features relate to a method of forward loop dialling over a two-way inter-office trunk and to the control of supervisory signals in the various kinds of call set up. The invention is described with reference to a system including manual pay-stations MPS, Fig. 1, automatic paystations APS of the kind described in Specification 158,276, and ordinary automatic subscribers. The toll recording and pay-station operator sets up ordinary calls for the manual pay-stations, and is reached over the tenth level of the first selectors, and notifies a toll operator of all toll calls. She may in emergency set up toll calls herself. The toll line TL-1 leads to a manual office and the line TL-2 terminates at each end in an incoming selector FSI. In setting up toll calls to automatic substations, the toll operator sets up a connection to the calling party over a special route FS4. TSR, C2 in which the connector does not ring the subscriber until it receives a, signal from the operator. Call from manual pay station MPS to automatic substation.. Line relay 202 lights lamp 204 and operates indicator 205 and its multiples. The insertion of the answering plug energizes sleeve relay 203, which puts out the line lamp but holds the indicators. The operator then throws the speaking key K10, and, on hearing the coin drop, inserts the calling plug in a jack such as J2 connected to a line switch. Sleeve relay 221 bridges the trunk through impedance 223 and one winding of electropolarized relay 222, which shunts the high resistance upper winding of the sleeve relay by its low resistance lower winding, thus lighting a lamp 217. The operator now throws the calling side dialling key K4, which energizes cord splitting relay 216 and relay 222, which shunts the condenser in the operator's set. Relay 221 is now shunted out and short-circuits the condensers in the jack circuit and the automatic switches are now held over dial spring 221<1>. After dialling, the operator restores key K4, relays 222<1>, 216 holding momentarily to give time for relay 221 to re-establish the holding bridge, and then key K10. When the called party replies, relay 222 falls back and lamp 217 goes out, and when he hangs up it lights again. When the calling party hangs up, line relay 202 shunts the high resistance winding of relay 203 by its low resistance winding, lighting lamp 212. The operator then throws keys K10, K1, shunting out sleeve relay 203, whereupon relay 201 disconnects the line relay and shunts the talking condenser in the line circuit. 110 volts positive is connected to both talking wires to operate magnet 250 in the direction to collect the coin. When key K1 is restored, magnet 250 disconnects itself from the talking circuits if the coin has actually been collected. The operator may throw the key a second time to ascertain whether the apparatus has operated correctly as indicated by a supervisory device in the coin battery circuits. Toll-call by manual pay station to manual office. The pay station operator answers the Toll-call by manual pay station to manual office. The pay station operator answers the call as before, tells the pay station to hang up, and gives the usual ticket to the toll operator, who, when ready, inserts a calling plug P4 in the jack J7 of a transfer trunk, whereupon relay 305 lights a lamp 245 at the pay-station board and the operator there inserts the answering plug PI of an idle cord in the jack J4, and the calling plug in the jack J1, whereupon relay 203 shunts its upper by its lower winding and lamp 217 glows. The toll operator inserts the answering plug P3 in a toll-line jack J5, and relay 302 disconnects relay 301 and operates indicator 303. She then throws the key K22, which projects ring- ing current over the toll line. When the wanted subscriber has replied she signals the pay-station operator either by withdrawing and re-inserting the plug P4 several times to flash the lamp 212, or by throwing the ringing key K19, which, in addition to sending ringing current, removes a shunt from resistance 317 to release relay 305. Relay 215, in response to the ringing current. intermittently removes a short-circuit from relay 214, which locks itself by opening a further point in the short-circuit and lights the lamp 212 steadily or through an interrupter (not shown). The pay station operator then throws her speaking key K10 releasing relay 214 to put out the lamp, and then her ringing key K9, which releases the sleeve relay 203, which cannot hold in series with resistance 219. Relay 201 then short-circuits the talking condensers and disconnects the line relay to give the ringing current a clear path. When the key is restored relay 203 pulls up and relay 201 falls. When the pay station answers, relay 202 puts out lamp 217. The operator then throws her speaking key and the answering side cut-off key K3 ta prevent the distant subscriber from hearing her conversation with the pay station party, who then inserts the necessary coins, which are collected by means of the key K8. When the pay station hangs up, lamp 217 lights and the operator throws the ring- ing key K12. Relay 313 responds and energizes relay 312, which remains up after being once operated and lights lamp 315 to notify the toll operator. Toll call by automatic pay-station to automatic office. In response to the digit 0 the first selector seizes a line terminating in a jack such as J3 before the pay-station operator, who, on seeing the lamp 241 glowing in response to the operation of relay 244, inserts the answering plug PI energizing relay 242, which extinguishes the lamp and cuts off a tone signal, which was connected up by the release relay 243 on the operation of relay 244. The operator then gives the ticket to the toll operator and the pay-station hangs up releasing relay 244, which lights lamp 212 and the plug is removed. The connection would then ordinarily be set up by the) toll operator, but at busy times the pay-station operator whose board is adjacent to the toll board can take a hand. In this case she inserts one of her calling plugs P2 in a toll service jack such as J8, and relay 324 which does not pull up until the plug is fully inserted, bridges the trunk. Relay 325 on the bridge energizes relay 326, which short-circuits its upper winding to light the lamp 217. She then throws the speaking key and calling side dialling key K4 to energize cord-splitting relay 216 and ground the sleeve of the plug, whereupon relays 326, 324 fall back in succession. The switches are now under control of the dial 221<1> and the operator seizes the paystation but does not ring it, and then inserts the answering plug in the jack J6 of a toll line such as TL-2, whereupon relay 411 disconnects relay 412 (lower) from across the wires 437, 438 and connects up the talking wires from the jack in its place. At the same time relay 414 is energized over 322, operates the multiple busy indicators 323, and connects battery and ground to the wires of the toll line in place of the impulse relay 415. At the distant end the bridged impulse relay pulls up and prepares the selector. The operator can then ring over the toll line to attract an operator to complete the connection, or she can set it up herself. To do this she throws her speaking key, and then the answering end dialling key K5, which operates relays 216, 221<1> and shunts out relay 411. which inserts the cord and dial between the battery 413 and the upper wire of the toll line. When dialling is complete, the key K5 is restored, and relay 411 pulls up again. The operator then rings the pay-station by throwing key K9, which removes a short-circuit from resistance 219, whereupon relay 326 falls back, but relay 324. which is more sensitive, remains energized to maintain the loop. Relay 326 short-circuits a pair of small condensers in the talking circuit provided to prevent premature signalling of the originating party by ringing current from the distant office. When the pay-station answers, the feed for relay 325 is interrupted in the transmission selector repeater TSR, Fig. 1, in well-known manner, and relay 325 disconnects relay 326 and lamp 217 goes out, being unable to glow in series with both windings of relay 324. The calling party then deposits coins and key K8 is thrown to collect them. When the pay-station hangs up the transmission selector repeater re-operates relay 325, lamp 217 glows again, and the operator takes down the connection. Incoming automatic call over toll line TL2. The distant operator plugs into a jack like J6, thereby cutting out a selector like FS1 and putting a source of current across the toll line. In the incoming selector, line and release relays 415, 416 pull up and the multiple busy indicators 323 are operated. Relay 415 repeats the first digit to vertical magnet 421. Stepping relay 418 pulls up and locks itself when the vertical springs change over, and on the relapse of the series relay 417 hunting proceeds in the usual manner. Additional springs energize relay 411, which cuts the locking circuit of relay 412 to prevent a signal from being given if relay 412 responds to the dialled impulses. Subsequent digits are repeated by relay 415. When the connection is taken down. relay 415 releases the switches ahead and relay 416 releases the incoming selector. Should the selector be unsuccessful, 11th step springs send back busy tone. Tandem call from toll line TL-2 over toll line TL-1. Inst