Patent GB-274518-A (GB)
Title: Improvements in telephone systems
IPC: H04Q3/00
Filed: 1927-07-19
Abstract: 274,518. Associated Telephone & Telegraph Co., (Assignees of Stehlik, R. F.). July 19, 1926, [Convention date]. Automatic and manual exchange systems.-A register-controller for use in networks including automatic and manual exchanges, in accordance with the exchange designation, either transmits the usual regular impulse trains comprising routing and numerical digits, or first sends routing digits to extend connection to a manual exchange and then transmits code impulses to operate a call indicator thereat. Where calls to certain manual exchanges are completed by way of a tandem manual exchange, the designation of the wanted exchange is coded to a call indicator at the tandem exchange, where the operator communicates over an order wire with the wanted exchange operator who assigns a trunk and completes the connection. In the system illustrated, Figs. 1 to 13 should be arranged as indicated in Fig. 14 to form a single circuit diagram. In a call to a manual office reached through a tandem manual office, or to a subscriber in the tandem office itself, a discriminating relay 901, Fig. 10 in the register-controller is energized over the fourth wiper of the exchange register OR, Fig. 8, so that after the transmission of the routing digits necessary for extending connection to the tandem office, the out-impulsing contacts of the regular sender SS, Fig. 7, are short-circuited, but two code registers CRI, CR2, Fig. 9, are set in accordance with the cross-wiring from the fifth and sixth contacts engaged by the exchange register OR. When the units register U, Fig. 9, has been set, the loop from the register-controller is momentarily opened to signal the tandem operator, who then connects up her call indicator, Fig. 5, thereby causing the feeding bridges to be cut out at the intermediate automatic exchanges, and a direct switch-through established to the call indicator. The code sender SS', Fig. 10, is then started and code impulses are sent in accordance with the cross-wiring between its contacts and the contacts engaged by the wipers of the code registers CR1, CR2 and by the lower wipers of the numerical registers TH, H, T, U, Fig. 9. Timing relay groups Tl, Fig. 2, and T2, Fig. 3, at the intermediate automatic offices terminate the direct switch-through after an interval sufficient for the code transmission. The tandem operator notes the wanted exchange as recorded on the first two lamp banks of the call indicator and either communicates the wanted number to the terminating exchange operator or plugs into the wanted line, as the case mav be. In a direct call to a terminating non-tandem manual office, no exchange code digits are required and the registers CR1, CR2 are not used. A discriminating relay 902, Fig. 10, is energized in place of the relay 901 to cause the code sender SS<1> to skip to the position in which the numerical digits begin to be coded. According to a modification illustrated in Figs. 11 to 13, in place of the timers T1, T2, an impulse of 400 cycle current sent from the register-controller when the code transmission is completed operates tuned relays at the intermediate automatic exchanges and terminates the direct switch-through condition thereat. Other features described but not claimed herein form the subject-matter of divided Specification 288,996. Local automatic call; normal operation of the register-controller. On removing his receiver, the calling party is extended over his line switch, the trunk circuit TC1, Fig. 1, and a non-numerical switch DS to an idle reaister-confroller, Figs. 6 to 10. The line relay 51 of the first selector 51, Fig. 1, energizes over the impulsing loop 35, 36 in the register-controller which is prepared in the usual manner by the response of its release relay 622, Fig 7., over the earthed release wire 37. The two office letters are recorded on the exchange register OR, Fig. 8, and the numerical digits are received by the numerical registers TH, H, T, U, Fig. 9. When the incoming control sequence switch S, Fig. 6, arrives in its third position, the impulse con. ductor 509 is grounded over wiper 530 of the outgoing control sequence switch 51, and the impulse relay 623, Fig. 7, intermittently energizes over the interrupter 626 to start the regular sending switch SS, and after the energization of the pick-up relay 624, interrupt the impulse circuit at armature 635. It is assumed that the exchange register has been set on contacts 721, Fig. 8, and as only one routing digit 3 is required, the first contact is connected over the frame IDF to the third stop conductor, whilst the remaining contacts are connected to the skip conductor 501. Accordingly, after the transmission of the digit 3 in the first position of the switch S<1>, this switch skips to its seventh position, and in positions seven to ten the numerical digits are sent in the usual manner. Known arrangements are provided for preventing the sending apparatus from catching up the recording apparatus. The routing digit operates the first selector S1, Fig. 1, and the numerical digits the usual switches to extend the connection to the wanted line. At the end of the transmission of the units digit, the switch S<1>, Fig. 6, earths wire 508, energizing relay 621 which at armature 627 grounds the conductor 38 to close. a circuit for switching relay 12, Fig. 1, which locks to the release wire, disconnects the register-controller, which restores in known manner, and connects impedance 9 and the right-hand winding of polarized relay 8 across the speaking wires. When the called party answers, the response of relay 8 may be used for metering purposes. Release is effected in the usual manner when the calling party hangs up. Call through tandem manual office; extension of call to tandem office. The register-controller is taken into use and the exchange register and numerical registers set as before. Since three routing digits are required it is assumed that the office register OR. Fig. 8, is set on contacts 723, the first three of which are cross-connected to stop conductors 1, 3 and 8 respectively. After these three digits have been sent, when the switch S<1> arrives in its fourth position, a circuit is completed over the fourth wiper and conductor 701 for a discriminating relay 901, Fig, 10, which locks to the earthed conductor 608, connects conductor 701 to the skip conductor 501 over conductor 702, causing the switch S' to advance to its fifth position, and at armature 910 puts a further shunt across the sending contacts 635, Fig. 7, of the regular sender SS. Accordingly, when the pick-up relay 624 pulls up on the sender SS operating for the fourth time, no impulses are. sent to line but an impulsing circuit is completed for the stepping magnet 803, Fig. 9, of the first code register CRI over 606, 637, 640, 645, 610, 803. Relay 801 responds on the first impulse and transfers the impulse circuit over its own armature. Since the fifth wiper of the exchange register OR, Fig. 8, is cross-connected to the fifth stop conductor, five impulses are delivered to the code register CRI, after which relay 801 relapses and transfers the impulse circuit to the stepping magnet 805 of the second code register CR2 to which four impulses are sent by the sender SS with the sequence switch S<1> in its sixth position. When the switch S<1> advances to its seventh position, earth is disconnected from the start conductor 509 (earth being disconnected from conductor 503 at armature 909, Fig. 10, even if the hundreds register H is off-normal) : no further operation of the regular sender SS can therefore take place. The first routing digit operates the first selector S1, Fig. 1, to select an idle trunk 75, 76 to the automatic office No. 2 where the incoming selector S2, Fig. 2, responds to the second routing digit and selects an idle trunk incorporating a repeater R1. The line and release relays 109, 110 energize to hold the selector S2 and close a bridge including the left-hand winding of polarized relay 108 and relay 114 across the outgoing trunk, thereby preparing the incoming selector S3, Fig. 3, at the automatic office No. 3. The third routing digit is repeated by the line relay 109 to the selector S3, the relay 113 being energized during the impulse series to complete a more direct bridge across the outgoing trunk and to disconnect relay 112. In automatic ex. change No. 3, the selector S3 selects an idle trunk to an operator's cord, the line and release relays 212, 213 of the trunk circuit TC2 being energized to hold the selector S3 but no bridge being completed across the trunk at this stage. In the register-controller, when the units register U, Fig. 9, or the second code register CR2 has been set, whichever happens last, a circuit over the off-normal contacts of the units register, conductors 504, 510, armature 641, and conductors 609, 806 is completed for relay 903, Fig. 10. which energizes relay 904 and at armature 919 opens the impulsing loop to line. Relay 904 pulls up after a slight interval and energizes. relay 907 which closes a new bridge including its lower winding across the impulse wires 604, 36, and energizes relay 906 which locks to conductor 608. This momentary opening of the impulsing loop is used to signal the operator that a call is awaiting transfer to the call indicator, in the following manner. When the loop is opened, relay 212, Fig. 3, relapses and energizes relay 217 over its lower winding, this relay energizing relay 216 and completing a bridge including its own upper winding across the outgoing trunk 241, 242 whereby the line relay 302, Fig. 4, of the operator's cord CCl is energized and lights a calling lamp 307. Transmission of code impulses. The operator depresses key P and holds it operated until the number comes in. Relay 301 grounds common conductor 355, connects relay 304 to conductor 357, and transfers the incoming trunk 241, 242 to the signal conductor