Patent GB-182533-A (GB)
Abstract: 182,533. Relay Automatic Telephone Co., Ltd., and Edwards, W. D. March 30,1921. Automatic exchange sy.stems.-The whole designation of a wanted line is recorded and retransmitted in succession from one to another of a number of serially related exchanges until the exchange in which the wanted line terminates is reached. The invention is described as applied to an arrangement of five exchanges A - - E, connected in tandem by junction lines as shown in Fig. 1. The exchanges A, B, C, D are connected in series, but direct trunks are provided between the exchanges C and E. A call originating at the exchange C is forwarded in either of the three directions B, E, D, according to the number called. or again a call received at the exchange from exchange B, for example, may be forwarded in either direction E, D, or may be completed locally. The internal switching arrangement, at the exchange C is schematically illustrated in Fig. 2, but the other exchanges are arranged on similar lines and the switching operations subsequently described as taking place in them may be conveniently followed on this diagram. General operation, Fig. 2. A subscriber SL local, say, to the exchange B, on removing his receiver to make a call is connected in known manner over a junction OT incoming to the exchange B and a connector RC thereat, to an idle recorder R, which, on the wanted number being dialled, energizes selected marking wires leading to a discriminating marker M, where a marking circuit individual to the wanted number is completed. If the call is a local one, the marking circuit extends over a wire SMW, and the connection is completed over connecting stages in known manner, but if the wanted line terminates in a distant exchange, say D, the circuit marked out in the marker M energizes a discriminating relay which extends the marking wires from the recorder R to an impulse storer IT in which the wanted number is recorded. The impulse wires IW from the storer IT are connected to an idle trunk OJ outgoing to the next exchange C where a recorder CS is taken into use, the calling line at the same time being extended at the exchange B over connecting stages OLC, OJLC to the contacts of a relav IPH associated with the engaged outgoing trunk OJ. The recorder and marker are now released at exchange B and the record on the impulse storer IT thereat is transferred to the recorder CS at exchange C, after which the storer IT is released and the calling line is extended over the connecting stage IPH at the exchange B, to incoming junction equipment IJE at exchange C. The recorder CS at exchange C then sets a marker M and impulse storer IT, and the same cycle of operations as has already been described with reference to the exchange B is repeated to transfer the wanted number to a recorder CS at the exchange D and extend the calling line to a trunk IJ incoming to the exchange D. As the wanted line terminates in the exchange D, the discriminating marker M thereat completes a marking circuit over a wire SMW and causes the completion of the connection to the wanted subscriber over connecting stages IJC, IJLC and ILC. By using variable digit recorders, as described in Specification 181,119, subscribers may be given numbers having varying numbers of digits according to the size of the exchange in which they terminate. The above connection is described in greater detail below with reference to Figs. 3 to 6, 8 and 9, which should be arranged as shown in Fig. 12. Where similar apparatus is used in two or more exchanges, the circuits in each exchange are traceable on the single figure given. Connection to an idle recorder at the originating exchange B over a repeater set and recorder connector, Fig. 9. The calling subscriber having become connected to an idle repeater set in known manner, a loop is placed across the calling line and the relay I, Fig. 9, is energized in a circuit 1. A relay G is thereby energized to close a circuit for guard relay GX, which marks the repeater set busy by opening circuit 5, and energizes the starting relay F1 of an associated recorder connector over circuit 6. Relay F1 locks up and completes circuits for the connecting relays RC1, RC<2>, &c. associated with idle recorders, the relay RC1 of the first idle recorder locking up and extending the calling line to it, and at the same time de-energizing the starting relay F1 and the other connecting relays RC<2>, &c. Setting of the recorder, marker, Fig. 5, and impulse storer, Fig. 6, at exchange B. The recorder taken into use at the exchange of origin B is one of the type responsive to numerical impulses, such as that described in Specification 181,119, and on the wanted number, say 209, being dialled, battery is connected to a hundreds, tens, and units marking wire HM, TM, UM, Fig. 5, in the manner described in the said prior Specification. Circuits 8 and 9 are thereby completed for a hundreds marking relay HDM2 and a tens marking relay TNM20, and a units marking relay UMR9 is energized in series with a discriminating relay ITS3 in a circuit 10. The relay ITS3 extends the marking wires to the impulse storer, Fig. 6, over circuits 11, 12, 13, and corresponding hundreds, tens and units recording relays HSR2, TSR0, and USR9 are energized, which lock up over circuits 14, 15, 16 in which relays HSS, TSS, and USS also respond. If the wanted line had terminated in the exchange B, the point y in the marking circuit 10 would have been connected to the line equipment of the wanted subscriber instead of to the discriminating relay ITS3. Connection of impulse storer IT at exchange B to an idle recorder CS at exchange C. Relay ITS3, Fig. 5, also closes a circuit 17, which in the manner described in Specification 181,120 causes the marking relay OJM, Fig. 8, associated with the first idle outgoing trunk to the exchange C, to lock energized and connect the calling line over connecting stages OLC, OJLC, Fig. 2, to the contacts of the associated impulse wire connecting relay IPH, which is also energized at this time and extends the impulse wires IW of the impulse storer IT to the outgoing trunk OJ taken into use. If trunks extending direct to other exchanges also radiated from exchange B and the wanted line terminated in one of these exchanges or was reached over one of them, the marking circuit 10 would extend to a different discriminating relay, ITS1 or ITS2, the energization of which would cause an idle outgoing trunk to the wanted exchange to be seized. After an outgoing trunk OJ has been seized, the cut-off relay RCO, Fig. 9, of the recorder connector is energized in the holding circuit 52, initiating the release of the recorder connector, the recorder and the marker at exchange B by interrupting the circuit 6. Relay IPH disconnects the calling line from the trunk OJ, but maintains an earthed loop over the A and B wires, thereby holding the connection over the repeater set, Fig. 9, by maintaining a balance of current over the windings of the relay IS. A relay IM in the impulse storer IT, Fig. 6, at exchange B is also energized in circuit 21 in series with a relay A of the junction equipment, Fig. 3, in which the trunk OJ terminates at the exchange C, thereby completing a circuit 24 for the starting relay F1 of the associated recorder connector, which selects and prepares an idle recorder CS at the exchange C in the same manner as did the recorder connector at the exchange B. The impulse storer at exchange B prepares itself to transfer its record, by the energization of relay IMR, Fig. 6, in circuit 22. Transfer of numerical designation from impulse storer IT at exchange B to recorder CS at exchange C. On the seizure of a recorder, Fig. 4, at exchange C, its preparing relay P locks up over a circuit 26 in which a switching relay A in the incoming junction equipment, Fig. 4, is also energized. The relay A extends the impulse wires IW from the impulse storer, Fig. 6, at the exchange B to the recorder, Fig. 4, at the exchange C, and combinations of impulses are sent over the impulse wires IW in accordance with the setting of the impulse storer, Fig. 6. These impulse combinations are first received by a relay group (shown to the left of Fig. 4) which selectively connects battery to one of the ten leads 1 - - 9 and 0, adapted to be extended to the hundreds relays, tens relays, or the units marking wires by guiding relays DM1, DM2, DM3. The relay P having prepared the recorder for the hundreds combination impulses by the energizatior of relays DC, DM1 in circuit 27, as in the call under consideration, the hundreds relay HSR2 in the storer is energized, an impulse is first sent to the relay 1IB over a circuit 21, 31. Relay 1IM is thereby energized and completes a circuit 35 for relay c, which locks up and closes circuit 37 for relay 1ICO. Relay 1ICO locks up, interrupts circuit 31, causing the relapse of relays 1IB, Fig. 4, and 1M, Fig. 6, and a circuit 38 is completed for a change-over relay MCO1, which transfers the impulse wires IW to a second combination of contacts of the relay HSR2, and energizes relays 2M, 2MR in circuits similar to the previously described circuits for relays 1M, 1MR. At the same time the impulse wires IW at the recorder, Fig. 4, are transferred from the relays 1IA, 1IB to the relays 2IA, 2IB. Impulses are now sent over both wires IW (in accordance with the second combination of contacts of the relay HSR2), relays 2IA, 2IB are energized, and a circuit 40 is completed for relay ICM, thereby completing a circuit 41 for the appropriate hundreds relay HD2.7 of the recorder. Relay HD2.7 locks up and breaks the circuit 27 of the relays DC and DM1 to restore the relav selector, the latter as it falls away completing another circuit 43 for the relay DC in series with relay DM2, which transfers the wires 1 - - 9 and 0 to the tens relays, thus preparing the recorder for the tens combinatio