Patent GB-352096-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone exchange systems
IPC: H04Q3/62
Filed: 1930-04-09
Abstract: 352,096. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London.- (Hatton, W. and Rousseau, E. J. ; 46, Avenue de Breteuil, Paris.) April 9, 1930, No. 11302. [Class 40 (iv).] In a system employing call-fingers for extending calling subscribers lines to exchange apparatus, in the event of a special type of call being required the ordinary call-finder is replaced by a call-finder giving access to the special apparatus required. A private branch exchange system is described in which four special call-finder groups are provided dealing respectively with conference calls, preference calls, code ringing of subscribers, and outgoing junction calls when all junctions from the main selectors are busy. Certain of the subscribers are not allowed exchange facilities and should these subscribers dial the exchange digits, they are connected to the manual operator. Normal operation, local call. When a call originates L, Fig. 2, operates and U pulls up completing a circuit for one relay Ra in a free link circuit, Fig. 3. Ra completes a circuit for PF and when the calling circuit is reached Gt in the register circuit operates over brush d from battery at el, Fig. 2. Relay Gt1 pulls up followed by Lb, A, and Rb. Relay Rc energizes, closing the c wire circuit and Co, Fig. 2, operates, disconnecting L. The a and b wires are connected to relay Is and dialling tone from wiper f of SM1 is connected to the calling subscriber. The first digit is repeated by Is to SM1, relay Lm operating in series with SM1, and when the train terminates Lm releases and Hs operates. If the first digit is 2, relay Hs completes a circuit for Hs1 over e of SM1, if 3, Hs2 pulls up and if 4 Hs1 and 2 both energize locking in each case to a5 to mark the hundreds digit. Neither relay is energized if the first digit is 1. Relay Hs also changes over the impulsing circuit to SM2 and the next digit is stored on this register, Lm operating on the first impulse. When SM2 moves off normal a circuit is completed over f of SM2 and a of SM1 for SM1 to restore to normal. When the second digit train finishes Lm releases and when SM1 has reached normal Fs pulls up releasing Hs and connecting Gt to wiper b of SM2. A separate power magnet PS1, PS2, &c., is used for each hundred lines, the one selected depending on which, if either, of the relays HS1 or HS2 is operated, and this magnet is energized stepping the link circuit wipers in search of the terminal marked in d1 by wiper b of SM2. When this line is reached Gt operates breaking the magnet circuit. In the meantime the release of Hs reconnects the impulsing circuit to magnet SM1 and the units digit is stored. After the 10's selection is completed, if the units digit is stored, Hs reoperates and Uc pulls up changing over the circuit of Gt from wiper b of SM2 to b of SM1. If the units digit is O relay Gt remains energized but for other digits Gt releases and PS1 or 2 &c. is again energized to step the connector wipers in search of the marked line when Gt energizes as before. Gt1 pulls up, energizing Es, disconnecting the stepping circuit and connecting the wiper c1 to relay Ft. If the called party is free Ft operates disconnecting the busy tone relay Bt and operating D. Rc and Lc in the link circuit energize, relay Rc connecting ringing to the called line. Relay Lc provides a through conversation circuit and connects As and Cs to the line, the latter relay acting as a ring trip relay. Relay D also opens the circuit of the register connect relays to release the register. When the called party replies Cs operates and Rc releases providing a speaking circuit. Calling party release is provided, the relay As de-energizing when the calling party hangs up, releasing E and Lc. Outgoing junction call via local link. The circuit operates as before described and the first digit, which is O, is recorded on SM1. Relay H operates via e of SM1, energizing the selector magnet, such as PS1, on whose arc the junctions are connected, and the wipers move in search of a free junction. When this is found Gt energizes s over d1 of PS1 and f of SM1 opening the circuit of PS1 and energizing Gt1. Relay D pulls up, energizing Oj, to provide a through metallic connection, and releasing Rb to release the register. Restricted service. If the caller is not allowed junction service then, when relay H operates, as described above, a parallel circuit is completed for Rs, over e of PF, to the subscriber's call lamp CL, Fig. 2. Relay Rs releases H and the lamp CL lights. When the operator enters the circuit, full ground is connected to the c wire releasing the automatic apparatus. All junctions from link busy, connection over special trunk finders. If all junctions connected to the link are busy, when wiper c1 of PS1 reaches the contact following the last junction J operates in series with Gt, stopping the switch, releasing H and energizing D. Lc energizes and Rb releases, freeing the register. The operation of Lc with PS1 normal completes a circuit for start relay St, Fig. 5, which pulls up and energizes the relays H of all junction finders associated with free circuits. If all junctions are busy Bt operates, over a chain circuit of h1 contacts, connecting busy tone to the calling subscriber. The operation of H enables PF to hunt for the calling line when Gt energizes followed by Gt1 Lb pulls up and C energizes connecting earth to wiper c to release the local link, whereupon Gt and Gt1 release and E operates. F pulls up in series with the subscriber's loop and the line relay at the distant exchange. When the calling subscriber releases, F de-energizes and Lb, C and E fall away releasing the circuit. Preference call. An initial digit 6 originates a preference call and when the impulses have been recorded on SM1, Lm releases and Hs pulls up, completing a circuit for Pl, Fig. 6, via Cc1, Fig. 8, and Cel, Fig. 7 (see Fig. 4). Magnet PF energizes stepping the preference line finder in search of the calling line when T energizes (over wiper d) stopping hunting and energizing Ta. Lb operates and A pulls up connecting the calling line to the stepping relay AS. Relay Ta also connects earth to the c wiper, releasing E, Fig. 3, and the link circuit. When the local link is released T, Fig. 6, falls back and E, Fig. 6, energizes, connecting dial tone to the calling line. The number is repeated by AS to registers SM1, SM2 as described above for Fig. 3, relays HS1, HS2 storing the hundreds digit to enable SMI to be used for both hundreds and units trains and the magnet PS1 or PS2 &c. sets the wipers a1 . . dl on the called circuit. Es energizes enabling the caller to listen on the circuit. To break down an existing connecting or to ring on the line the digit 1 is dialled the impulse being repeated by AS to Pa and Pb energizes. If the line is busy Pb connects ground to the calling party's c wire, forcing release of the existing connection, and connecting Cs to the called loop. If the line is free, or, if busy, when the called party clears and Cs releases, Rc energizes, ringing the called line. When the called party replies, Cs energizes releasing Rc and switching through. When the calling party clears, As releases and A and Lb fall back returning the circuit to normal. Conference calls. For a conference call the digit 5 is dialled energizing Ce, Fig. 7, (see Fig. 4) and PF hunts for the calling line, when T, Fig. 7, operates, energizing Lb and A. As is connected to the loop, as before, as soon as the local link is released and dial tone is returned to the calling subscriber. The impulse trains are repeated by AS to SM1 and SM2, relay Es being energized, if a hundreds digit outside the range is dialled, connecting busy tone to the calling party. When the wipers al .. e1 are on the terminals of the called circuit T and Uc are energized and Es pulls up, connecting Ft to the c wire of the wanted line. If the line is busy, busy tone from Bt is connected to the calling line. If free, Ft pulls up connecting ringing, via Rg, to the called circuit. When the called subscriber answers Rg energizes operating Rc, releasing Ft, and allowing c, in the called circuit, to energize and lock to the conference circuit. The calling party now dials 1 which is repeated by As to R. Relay R releases all energized relays except A, As, Lb and causes SM1, SM2 to return to normal. When SM1, SM2 are normal Ra energizes, releasing Rand E pulls up. The caller now dials the number of the next subscriber required for the conference call and the cycle of operations is repeated. When any of the called parties release, the relative C relay deenergizes disconnecting the line from the conference circuit. The caller may release from the circuit and re-enter by dialling the preference code followed by a reserved spare number. Code call. To make a code call the prefix 7 is dialled, energizing Cc, Fig. 8 (see Fig. 4), and when the calling line has been found by the call-finder, Fig. 8, relay T energizes releasing the link circuit, energizing Ta, Lb, and A, and dial tone is connected to the caller. A special code number is now dialled of which the first digit, which is either 5 or 6, is repeated by AS to SM1. The receipt of any digit but 5 or 6 connects busy tone to the calling circuit. If the first digit is 5, Lt operates over c of SM1 ; if 6, a circuit is completed for SM2 which rotates until terminal 11 is reached when Lt operates. When the train terminates Lm releases and when Lt energizes Cn pulls up changing over the impulsing circuit to SM2. The second digit is repeated to SM2 and when the train ceases Lm releases and St pulls up, closing a circuit for I. Relay I and magnet SM3 interact and when the brush b of SM3 reaches terminals marked by the brushes of SM2, relay Rr operates ringing the code bells. As shown 20 different codes are available. When the wanted subscriber hears his code he dials the special answering number