Patent GB-550235-A (GB)
Title: Improvements in telephone systems
IPC: H04Q3/00
Filed: 1941-06-27
Abstract: 550,235. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. June 27,1941, No. 8082. Convention date, Aug. 26, 1940. [Class 40 (iv)] A register-translator system which provides for automatic ticketing and which is generally similar in character to that described in Specification 530,443 is adapted to deal with calls to and from party-line subscribers. The system is designed for an area divided into zones, and an exchange is denoted by three digits, the first two being indicative of the zone, except in the case of a single exchange in a zone, which is denoted by the two zone digits only. The numbers of party-line subscribers contain an extra digit or suffix indicating the position on the line. General arrangement.-The layout for the exchange 381 is shown in Fig. 2. A calling line is connected over a line switch 40 to a primary selector 50 which takes into use a registertranslator 60. The selector 50 has access over one set of wipers to the local switches 51, 52, 53 and to junctions 482 leading to other exchanges in the zone, and over the other set of wipers to junctions 470 leading to other zones, to a zero operator's position and to a special service selector 54, which in turn has access to various operators' positions and to a revertive call switch 118. Each of the junctions 470 includes a toll ticketing repeater 80 which becomes associated with ticketing apparatus at the end of the conversation. If ticketing is required on calls to certain exchanges in the same zone, similar repeaters are included in the corresponding junctions 482. When the exchange designation received by the register-translator 60 indicates that ticketing is necessary, a pair of detectors 70, 71 are taken use to determine the number of the calling line. These detectors employ cross-bar switches and are identical with those described in Specification 530,614, Figs. 1, 2, 4, 5, 6. In the case of a call from a party line, the suffix digit is determined in a manner described below. The calling and called numbers, together with a rate digit, are sent from the register-translator 60 to the repeater 80 in code form over one leg of the control circuit, while the digits for setting up the connection are sent in the usual form over the other leg, as described in Specification 530,443. The transfer of information to the printer-controller and the operations of the latter follow the lines of that Specification. The code storage units in the register-translator, toll ticketing repeater and printer-controller comprise a number of individual magnets, four for each digit, all under the control of a master latching magnet, as described in Specification b49,243, [Group XXXVII], Specifications 516,409 and 550,244 also are referred to. General operation.-The detailed description in the Specification is illustrated by drawings, e.g. the primary selector is shown in Figs. 3-5, the toll ticketing repeater in Figs. 15-17, and the register-translator in Figs. 18-25. The following description is in general terms, but a few references are given by which certain parts may be indentified in the drawings. The dialled number may comprise 6-8 digits and eight registers A ..H are provided in the registertranslator 60 for storing them. The first digit is repeated over the negative wire to the primary selector, and if it denotes a special service call or a call to a zero operator, the register-translator releases and the selector hunts in the first or tenth level. In the former case, the special service selector 54 drops back in response to the second digit which is invariable and hunts in the level denoted by the third digit. If the first digit has any other value, the selector drops back in response to a ground connection on the positive wire and subsequently takes the third exchange digit if the first two digits indicate an exchange in the same zone. In the case of a call which does not require ticketing, a resistance ground is applied to the positive wire to effect wiper switching, the selector hunts, the register-translator releases and the numerical digits pass directly. In the case of a call in the same zone which requires ticketing, the selector again drops back and remains under the control of the register-translator, which sends a single routing digit thereto. In the register-translator, on all calls that require ticketing, the A, B and C registers cause the choice of a wiper and the setting of a bi-directional code switch P, which by means of a jumpering frame marks a setting position for a bi-directional route switch R. The wipers of this switch are effective in turn to send a maximum of five routing digits, which are followed by the stored numerical digits. The detectors 70, 71 are seized while the route switch R is taking up its position, and the number of the calling line is transferred to a code storage unit in the register-translator, and, when the transmission of the setting digits is sufficiently advanced, the information for ticketing is sent over the positive wire in the form of ground and resistance ground impulses to a code storage unit in the toll ticketing repeater 80. This information comprises a rate digit determined by the route switch R, the called number recorded by the registers A .. H, the suffix if any of the calling number recorded by a register J as described below, and the number of the calling line. The register-translator then releases. The toll ticketing repeater includes a switch T for timing the duration of the call and a switch P which is under the control of the back-bridge relay and which grounds a wire Z leading to. the printer controller when the called subscriber dials O to bring about the printing of an extra character. Alternative routing.-If no idle outlet is found by the primary selector or at the next exchange, ground is returned over the positive wire to the register-translator to operate a relay (R 2130) which opens the negative wire to release the partial connection and advances the route switch R one step to select fresh routing digits. If more than two routing digits have already been sent, however, the busy condition results in the release of the register-translator and the primary selector switches through to busy tone. A busy condition at any stage of the alternative route also results in the release of the register-translator, since a busy relay (R2010) is already up. Two exchange digits only.-The register C takes the first numerical digit and therefore the ten positions to which the code switch P may be set are multipled together to mark a single position of the route switch R. The latter after sending the routing digits connects up a relay (R1910) which connects the wires for controlling the numerical transmission to the registers C .. G instead of to D .. H. Calls from party lines.-Subscribers are provided with a dial somewhat resembling that described in Specification 451,864. It is furnished with an extra finger-hole for sending 11 impulses over the negative wire, while, by means of cam-controlled contacts, ground is applied to the positive wire during a variable number of impulses according to the suffix digit of the subscriber's number. In the register-translator, the off-normal movement of the A register removes a short-circuit from a relay (R2000) which is connected up to the positive wire of the loop and which when energized cuts off the register J. A partyline subscriber requiring a toll call must first dial the digit 11, so that the relay in question remains short-circuited until the register J is set in accordance with the suffix digit, while the A register is set back to normal. If he fails to do this, a marginal relay (R1930) which is operated by booster battery from the line switch attached to the party-line applies a marking from the register J in normal position to the route switch R which selects the routing number 101 to direct the call to an operator's position.