Patent GB-565654-A (GB)
Title: Improvements in telephone systems
IPC: H04M15/04
Filed: 1943-05-14
Abstract: 565,654. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. May 14, 1943, No. 7685. Convention date, Aug. 6, 1942. [Class 40 (iv)] In an automatic ticketing system of the kind described in Specification 559,403 which caters for " extended service " subscribers who pay a higher flat rate than ordinary subscribers and are charged at a lower rate for toll calls, the charge for such calls being separately calculated in the two cases, provision is made whereby extended service subscribers are given free toll service to exchanges in adjacent zones, calls to those exchanges being therefore forwarded through toll ticketing repeaters or through ordinary repeaters according to the class of the calling subscriber. The primary selectors are divided into two groups, one group serving ordinary and party line subscribers TP, TS1 1 ... 4 and the other group serving extended service subscribers TX and subscribers who are denied toll service TD. In a selector of the first group, Figs. 6, 7, a strap 723 is connected so that the operation of relay R750 applies ground through a resistance 722 to wire C644. In a selector of the second group, 441, Fig. 4, on the other hand, the strap is connected to apply direct ground to that wire. The dials of party line subscribers other than first party are provided with auxiliary cams for sending a number of ground impulses to identify the party who is calling : such impulses are effective during the dialling of the second digit of the wanted number. The dials of subscribers who are denied toll service are arranged in an analogous manner to send two ground impulses for a reason which is explained later. The system is designed for an area divided into zones, each exchange being denoted in general by three digits, and differs from that of Speeifications 550,235 and 559,403 in that a registertranslator is not taken into use until it has been determined by the reception of the exchange digits in a primary register that translation is necessary. The latter then transfers the stored digits to the translator and repeats the subsequent digits thereto as they come in. Calls not requiring translation. When the primary register, Figs. 12-16, is seized by the primary selector, Figs. 6, 7, the loop is extended to line relay R1450, the line relay R730 of the selector being held over wire C642 which is grounded by guard relay R1240. The first digit sets the register A1500 and is repeated also to R730 to set the selector in which R750 energizes in parallel with the vertical magnet and holds over its upper winding to wire C644. The sequence switch S1630 advances one step. If the digit is 0, indicating a call to a manual operator, a circuit is made for R1430 which disconnects R630, R620 to drop the register and transfer the loop to R730, R750. The last relay falls back on account of the resistance of the loop and initiates rotary hunting. Similar action takes place if the digit is 1, being the first digit of a special service number, the call then being forwarded through a special service selector of drop-back type. In response to any other first digit, the removal of ground from C642 releases R730 and causes the selector to drop back. Relay R1440 transfers the loop to relays R1410, R1420 and the former repeats the second digit to the register B1510, whereupon R1440 restores and the third digit is repeated by R1450 to the register C1520 and also to R730 which finds a fresh circuit over the A and B registers. If the three digits indicate a local call or a call to a neighbouring exchange which requires no translation, R1430 energizes and the primary register is released as described above. Calls requiring translation. In this case the receipt of the first three digits in the primary register operates R1270 which causes the association of an idle translator, Figs. 17-28, over finder F2290. Relay R1340 energizes in the test circuit and connects up R1370 to start the transfer of the stored digits. Meanwhile, R1450 repeats the fourth digit to the register D1620, and on the next advance of sequence switch S1630 a circuit is made for repeating the subsequent digits over wire C1395, ground being applied to C1281 by dialling relay R1260 during each digit. If at this time no translator has become connected, busy relay R1380 operates. To transfer the first digit, pulsing relay R1350 steps the A register and sends over wire C1391 a complementary number of impulses from ground through resistance 1506 followed in position 10 of the register by a direct ground impulse. Three additional impulses are then sent, one or more of which may be direct ground in the case of a call from a party-line subscriber, as described later. Similarly, the second, third and fourth digits are transferred over wire C1392 by pulsing relay R1360 as trains of resistance ground impulses separated by direct ground impulses obtained from the 10th positions of the B, C and D registers. In the translator, switching relay R2280 closes a circuit over R750, C644, C1394 for marginal relay R2040 which is inoperative in the present instance. The impulses over C1391 control R2050, R2060 and the former sets the register A2400, while the latter which is marginal responds to the direct ground impulse or impulses and advances the party-line register N2620 which at its first step cuts off the register A2400. Similarly, the impulses over C1392 control R2110, R2120 and the former sets the registers B2410, C2500, D2510, while the latter being marginal responds to the direct ground impulses and controls sequence relays R2710, R2720, R2730. The B and C digits also go to the bidirectional code switch P2330, one wiper of which is selected by the A register to mark over a jumpering frame a setting position for a routing switch R2310. Meanwhile, the fifth, sixth and seventh digits are repeated over C1395 to the registers E2520, F2600, G2610, sequence relays R2740, R2750, R2760 being controlled over C1281. The sending operations are started by relay R1710, and the wipers of the routing switch are effective in turn to send up to four routing digits which may be followed when required by the A, B and C digits in untranslated form. The first routing digit goes over wire C2235 to line relav R730 of the primary selector (which dropped back twice after taking the first and third dialled digits), whereupon the operation of R1810 opens the holding circuit of R750 in series with R2040 to permit rotary hunting. Relay R1760 initiates the operation of the detector, which is described in a later paragraph. When the primary selector switches through to a toll ticketing repeater, Figs. 8-11, subsequent digits for setting up the connection pass over one leg to R960 while the information for ticketing is sent in the form of ground and resistance ground impulses to R910, R920 in the manner described in Specification 530,443. This information comprises a rate digit determined by the route switch R2310, the calling and called numbers, a digit identifying the translator and in certain cases a discriminating digit as mentioned later. Finally, R2210 and R1430 operate to bring about release of the translator and primary register. Detector, Figs. 29-38. The operation of R1760 connects up start relay R3210 of the detector which becomes associated with the translator over a relay finder 1F ... 6F. Switching relay R2850 extends the test wire of the calling line over C645, C1393, C2232, C3102 to transformer 3161 to which a tone frequency is applied. Pulsing relay R3230 operates relays 1K ... OK in sequence and these respectively connect up relays 1B ... 0B, each of which controls a group of 10 A relays, e.g. 0B controls 00A ... 09A. Each group of A relays extends 1000 S leads from the line circuits and these are further extended in groups of 100 by relays 0C ... 9C which are operated simultaneously by R3170 to 10 test conductors C3500 ... 9 and thence through amplifiers to test relays OR ... 9R. Thus, when a test relay responds to the tone frequency mentioned above, the K relay then operated denotes the thousands digit of the calling number while the particular R relay denotes the hundreds digit. It should be noted that subscribers on a party-line are given individual numbers which differ as regards the hundreds digit, and the circuit of each A relay includes one of four wires C3401 ... 4, one corresponding to private and first parties, one to second parties and so on, these wires being selectively grounded from the party-line register N2620, so that only those A relays actually operate that correspond to the kind of party who is calling. The operated R relay energizes the corresponding one of relays OS ... 9S and on the operation of R3290 markings are applied over contacts of the K and S relays to storage groups S2801, 2 in the translator. The operated S relay holds the corresponding A relay and energizes the appropriate one of relays 0D ... 9D to extend the group of 100 S leads which has been identified. Transfer relays R3710, R3810 are now operative and a fresh cycle of the K relays controls relays OE ... 9E which further extend the 100 S leads in groups of 10 to C3500 ... 9 and the R relays to determine the tens and units digits. The R relays this time control relay OT ... 9T, and a second operation of R3290 applies markings over contacts of the K and T relays to storage groups S2803, 4. Finally, wire C3201 is grounded to energize R2240 in the translator which starts the transmission of the information for ticketing and releases the detector. Should the K relays in either of the two tests operate through two complete cycles without making an identification, R3350 operates to connect up an alarm relay R3360 and to ground wire C3301. Relay R2250 responds in the translator, releases the detector and makes a circuit for directing the call to an operator's position, as described later. The detector remains out of service until reset key K3370 is actuated. Ticketing. The toll