Patent GB-799481-A (GB)
Title: Improvements in or relating to automatic telephone systems
IPC: H04Q5/00
Filed: 1956-09-24
Abstract: 799,481. Automatic exchange systems. GENERAL DYNAMICS CORPORATION. Sept. 24, 1956, [Sept. 26, 1955 ; Sept. 26, 1955], No. 29158/56. Class 40 (4). The system comprises party lines of different types in which the designations of the stations on the different types of line are arranged in different modes. When a party makes a call identifying means are conditioned, according to the type of party line, to operate in the appropriate manner to identify the calling party. The invention is described with reference to the Hudson office and a remote Russell office, both of which may comprise a number of exchanges. Each exchange has one or more trunk recorders for storing information concerning toll calls handled by its associated trunk circuit. Common recording equipment is provided, however, only in the Hudson office and is operated by playing back the information stored in the trunk recorders of both offices to produce printed or perforated tickets in respect of each toll call. Playback from the trunk recorders in the Russell office is transmitted to the common recorder in the Hudson office over v.f. channels. General operation of system, Figs. 1 and 2. Local calls are connected in known manner and are not ticketed. To make a toll call to a subscriber connected to an exchange in the Cleveland area, the calling subscriber dials an access digit indicative of the Cleveland area, selector 142 responding to this digit to seize a trunk circuit 126 extending to the Cleveland area. The subscriber next dials a party digit, which is the first entry made in the associated trunk recorder 127 and is not used for extending the connection. The trunk recorder is of the type described in Specification 757,125 and comprises an endless loop of magnetic tape having mark and space transducing heads adjacent lateral spaced areas of the tape. The party digit is recorded on the tape as a number of mark pulses followed by a space pulse. If the calling subscriber is on a private line this digit is arbitrary and has no significance. If, on the other hand, the calling subscriber is on a party line, this digit is his own party digit and is used in the determination of the directory number of the calling substation. The party digit operates a stepping switch in the trunk circuit 126 to energize one or more dialled party digit register relays. The calling subscriber next dials the code digits of the wanted exchange followed by the numerical digits of the wanted subscriber. These digits are recorded in the trunk recorder 127 in the form of groups of mark pulses separated by space pulses as shown in Fig. 120A. The stepping switch in the trunk circuit 126 counts the number of digits dialled and prevents recording of any digits dialled in excess of seven. Recording starting time. If the called line is busy, tone is returned and the connection released. If the called line is idle and is seized a supervisory relay in trunk circuit 126 pulls up to start rotation of a timer cam to restore the stepping switch and then advance it at the rate of one step per second. After a grace period of 8 seconds during which the calling subscriber may release the connection without change, a further supervisory relay operates to associate the trunk circuit 126 and trunk recorder 127 with a clock and calendar circuit 133 which transmits the date and time to the recorder. Identification of calling substation. The trunk circuit then grounds a common allotter start lead extending to an identifier sender allotter circuit 129 which associates an idle identifier sender such as 131 with the trunk circuit and with an identifier circuit 130. The allotter 129 also energizes an identification relay in the trunk circuit to apply an identification tone over an HS lead to a terminal or lead individual to the calling line circuit and selectively interconnected with an identification matrix 128 in accordance with the directory number of the calling substation. The indentification matrix comprises a terminal per line matrix and ten individual party matrices. When the calling loop was first extended to the trunk circuit 126 a test was made to determine whether the dialling device at the substation was conventional or of the modified type in which party identification is provided automatically by ground impulses during four rewind operations of the dial. In the latter case these impulses are counted automatically in the trunk circuit. If the calling substation is on a private line or on a party line in which service is provided on a terminal per line basis the identifier circuit 130 is directly energized from the terminal per line matrix when tone is applied to the HS lead. If, on the other hand, the calling substation is on a party line on which service is provided on a terminal per station basis appropriate thousands, hundreds, tens and units bus-bars corresponding to each of the parties on the line are energized in the individual party matrices and one of the party matrix selection relays is operated by the party digit register in the trunk circuit to select the individual party matrix and so extend the appropriate set of bus-bars to the identifier. The bus-bars fire corresponding tubes in the identifier to energize corresponding relays in the identifier sender 131. The identifier and identification matrix are then released. The identifier sender 131 has four groups of ten register sender relays which thus store the values of the four digits comprising the directory number of the calling substation. It also comprises a group of steering relays which permits each group of register sender relays to restore sequentially and transmit groups of mark pulses to the trunk recorder with space pulses interposed between. After transmission the identifier sender is released. If the identification received by the sender 131 is inadequate, a no-identification relay in the trunk circuit 126 pulls up to apply busy tone to the tip and ring conductors of the extended connection and to cause the trunk circuit to apply an endof-call signal COE to the trunk recorder. The identifier sender then sends four space pulses to the trunk recorder and the calling subscriber releases the connection. Timing duration of call. Assuming that the call is established and identification made, then operation of supervisory and supervisory-assist relays in the trunk circuit operates a timer clutch in known timing mechanism which provides a mark pulse after slightly more than one minute and subsequently at one-minute intervals. These pulses are recorded on the magnetic tape until the trunk circuit sends an endof-call signal COE followed by a series of space pulses to separate the recordings of successive calls. Calls to Akron area. For calls to the Akron area two access digits must be dialled, the first seizing selector 146 and the second trunk circuit 135. Calls from Russell office. The Russell office may comprise one or more exchanges and has common information collecting and storing equipment 245 comprising identification means, trunk circuits and trunk recorders similar to those in the Hudson office. Operation of system to make printed or punched tickets in respect of toll calls. To make a permanent record of the calls stored in both the Hudson and Russell offices a common recording equipment is provided in the Hudson office. It seizes each trunk recorder such as 127 and 136, in the Hudson office, sequentially to cause transmission of the required information to a recorder 220. This recording equipment can also be connected over a carrier link to trunk recorders in the Russell office. At a selected time the clock and calendar circuit 133 operates read-out control circuit 210 to advance stepping switch 210a to gain access to one of a number of playback control circuits such as 200. The circuit 200 hunts for and seizes in sequence the trunk recorders to which it has access. When trunk recorder 127 is seized, the readout control circuit 210 resets register circuits 240, 250, 260, 280 and 290 and charge computer 270. Playback control circuit 200 also completes a path from the transducer heads in the trunk recorder 127 through an amplifier to common mark and space conductors 211, 212, the latter extending to a steering circuit 230. A clutch magnet in the trunk recorder also energizes.to advance the magnetic tape rapidly to home position indicated by perforations 12001-12003 and thereafter to advance the tape continuously with simultaneous read-out and erasure of the information on the tape. The space pulses appearing on conductor 212 advance a gas tube counting chain in steering circuit 230 step by step. These tubes are connected to drive tubes in the registers 240-260, 280 and 290 so that the groups of mark pulses read out from the trunk recorder are directed as required to the clock and calendar register circuit 280, the calling station number register 260, the called station number register 250, the called exchange register 290 and the elapsed time register 240. Each of these registers comprises a number of gas tube counting chains. The first item of information in respect of each toll call is the party digit which is directed to the calling station register 260. The next three space pulses direct the succeeding groups of mark pulses to three counting chains in the called exchange register 290, an exchange code interpreter circuit 295 being connected to the anode circuits of these counting chains to translate the dialled digits into the two alphabetical and one numerical character required for exchange identification. The exchange interpreter 295 also signals a rate and route marking circuit 275 which also receives from the playback control circuit 200 or the readout control circuit 210 information concerning the called exchange whereby the rate of change may be ascertained and sent to a charge computer 270. The rate and route marking circuit also indicates to the calling station numb