US1239097A - Telephone system. - Google Patents

Description

G.' ABt. TELEF/HONE SYSTEM.

APrucmon mio Amma. Isls. Patentedsqpt. 4 1917' iQ flEfIf-suezr l.

G. GRABE.

TELEPHONE SYSTEM. APPucmon msu Aucas. lala. 1,239,097, Patented Spt. 4, 1917.

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TELEPHONE SYSTEM.

APPLICATION FILED AUG.28. WIB; 4, Y

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G. GRABE.

TELEPHONE SYSTEM.

APPLICATION min Aus.26. 1913.

5 SHEETS-SHEET h 1,239,097. Patenf' Septl 4, 1917.

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TELEPI'IUNE SYSTEM. APPLICATION FILED AUG|26` ISIS.

Patentd Sept. 4, 1917.

GEORG GBAIBE, 0F NIKOLASSEE, NEAR BERLIN,

HALSKE, A. G., 0F BERLIN, GERMANY, A

GERMANY, ABSIGNOR TO SIEMENS &

CORPORATIN OF GERMANY.

TELEPHONE SYSTEM.

' Specification of Letters Patent.

Patented Sept. 4, 1917.

Application-tiled August 26, 1913. Serial No. 788,697.

To all Awlw/ln t may concern:

Be it known that I, GEORG GRABE, a German citizen, and resident of Nikolassee, near Berlin, Germany, have invented certain new and useful Improvements in Telephone Systems, of which the following is a speciication.

My invention relates to that class of telephone systcms in which automatic or semiautomatic devices are employed for first establishing a preliminary connection between two points of a telephone plant and in employing thereupon other such means for establishing a talking connection between said points over a shorter path, While the preliminary connection is released, More particularly my invention relates to the means of establishing the talking connection. My present invention considers the .establishing in any known manner of a preliminary connection and then the set ting up of the switches of the second connection by impulses sent out from a point of the preliminary connection, the number of said impulses corresponding to the points to be connected by the talking connection.

The specification of my invention refers to' a system in which talking connections for long `distance conversations are to be established. I Wish it understood, however, that the invention distance conversations but that the talking connections ma also join subscribers of a local ofice or o ces.

My present invention also refers 4to details of establishing the talking connection as will more clearly appear with reference to the descriptions.

Referring now to the particular application of my invention to lon distance connections I elnploy selectors ogs construction: as used for local service also for making long distance connections. This is accomplished by connecting the long distance lino with a line for local service made bu over a selector or multiple contact (subscri er selector or multiple contact for subscriber selectors by a back-selecting circuit from any desire point of the connection (subscribers station or operators place) which is possiblc over selectors which are controlled from the trunk line oflice by an additional combination of current impulses.

To provide special circuits for the! long distance service results in special advanbe not restricted to long ice, then,

tages; If in a local office with 5000 subscriber connections there be, for instance, 500 groups each having ten line selectors and 100 connections for long distance servfor establishing a long distance connection it would be necessary to use first, second and third group selectors in order to reach a line selector. According to this invention, now, in the circuit leading over these group selectors only one preliminary connection with the line selector or with the desired subscriber line itself is established. From the place thus reached a circumventing connection will then be made which for the aforesaid example will only require a so-called hundred-system, as only one of the 100 long distance connections has to be chosen. The circumventin connection in this circuit is therefore s orter than the preliminary connection.

Accordmg to this invention the preliminary connection contains .only those switching instrumentalities which prepare a subscriber selector for the long distance service, While the switching instrumentalities for properly establishing the long distance connection are advantageously associated with the circumventing connection, because in this case the selectors of the longer preliminary connection which have been in use only for a short time may again be ymade free formaking other connections.

Still another advantage results from the employment of special switching connections for lonfg distance service, namely the possibility o using an improved' line construction such as by employin heavier copper strands or by addition o? Pupin coils. In case local and long distance service were united throughout the system, ing lines between the local offices would have to be made of superior construction, while by having separate connections such superior construction may be limited to lon distance connections. On the other han the same subscriber selectors may always be employed for either mode of operation; for in this case the subscriber lines are connected to these selectors, which lines do not need to be changed for long distance service. The employment of special switching connections for the long distance service by commonly using the subscriber selectors rovided for local-service will therefore a low not only the smallest number of lines to be all connect-V of switching connections must be led to t employed but also the smallest number of subscriber selectors.

lVhile it is not necessary to connect the special switching connections with the ordinary switching connections at the very point where the improved line construction ends, it nlay he found advantageous by considerations other than those of line construetion, to have the switching connectionsrnn '|'iarallel to each other on a still 'further part of the line.

In case, for instance, the lines coming in at a smaller oflice from the main ofiice, end at the latter officie in two group selectors,

then the long distance connections up to.

these selectors would have to be kept separate fromv the lines for local connections, while the sets of contacts for the second group selectors could be switched togetinlr. ln view of possiblelatcr arrangements of the long distance system it would further 4he desirable to provide also special third group selectors; in every case, however, hoth kinds il() same subscriber selectors.

My invention will he more fully understood hy reference to the accompanying dwwings which show the arrangements according to my invention only in a diagram matic manner,4 details such as circuits for switching, testing, `separating or other purposes being notfully shown. In the drawings, Figure 1 shows a system in which upon taking o'l" the receiver. a first and a second pre-selector will adjust themselves in succession upon the line calling, whereupon by means of current impulses from the calling station thc adjustmentl of a first. second and third group selector and a line selector is accomplished to connect to the desired subscriber line, Fig. 2 shows thc details of a long distance group selector used in the arrangement of Fig. l and its set of relays, Fig. 3 shows other details of the connections of Fig. 1, Fig. l represents diagrammatically the circuitsl for a long distance connection, and Fig. la another inanncr of arranging Said circuits, Fig. the circumvcnting connection forminga preparatory circuit for the long distance. connection', Fig. 6 an arrangement ofthis kind whereby only one place with apparatus Yfor sending impulses is provided for several long distance stations. Fig. 7 shows a connection of a numeral senders place over selectorsl with subscribers of the local oflice in which prei-selectors are associated with the subv scriber lines. Fig. 8 shows a similar arv rangement in which each pre-selector of a subscriber is provided with a resistance and a special switching lever in addition to the testing or separating relay and the call re lay. Fig. 9 shows in a diagrammatic Way' a long distance telephone system with local subscribersl differing from that of Fig. 8 in that the Ylocal subscriber lines arefconnt-ctcd at the local oilice to call seeker contacts and led over first and second call seekers, and Fig. 16 shows details of the connections of the arrangement according to Fig. i).

Similar reference, characters designate similar devices throughout the drawings; also for the salio of clearncss in the figures showing details of the connections I have indicated the relays by capital letters. while the contacts of these relays are designated bv means of corresponding small letters, and the reference numerals. Furthermore all switching instrumentalities are shown throughout the drawings 1n -thcn' position of rest.

llcfcrring now more particularly to the drawings, in the system of Fig. 1 thc connection between two subscribers T, and T2 is made in such a way that in taking off the receiver at the calling station T, a first preselector VW, and a second pre-selcctor VW, will adjust themselves in succmsion upon tlnI calling line, whereupon b v a combination of current impulses through numeral impulses sent from the subscriber station T, the rdjustmcnt of the group selector lGW', lfiilV land IILGVV and the line selector LW' will be established upon the line of; the desired subscriber 11. These selectors may be constructed according to the well known Strowger type. At F I have indicated a subscriber to a trunk line ofiicc. which may beconnccted to the local line over a third group selector' lllflVVF which is only accessible from the trunk linc oilice. At the selector lllliW' F a set of relays indicated by RS is provided by means of which the specific switching operation for long distance connections are effected.

The long distance group selector l'IlGWF and its associated set of relays RS of F ig. 2 and the details of the connections of the line selector LW which is connected to the selector IILGWF of Fig. 3 will operate as follows: For making a connection over the selector HLGWF and LW at the subscriber station l*` of the trunk line office a ground connection is made on the line c, whereby at the group selector IILGWF the relays 0 F; and ll, will respond in the following cir cuits: First-ground made at the trunk line office, line c, head contact i111, winding l of 0 winding "l of E, battery and ground; .Seremi-ground at the trunk line ollicc, line c, head contact k2, winding l of B battery and ground. The relay C, which inserts itself over its contact 10 and the shaft contact tv/c, into a' circuit which is ilidcpendent from lf, connects the impulse relay A1 over contact il with the line a and also the winding 2 of the relay B, with the line 0. As Bl has already responded over its winding l and'ovcr the line c and closed the contact 13, the winding 2 of B1 is also connected to the Jlfi line b over 12and 13. Relay B1 furthermore has closed its contacts 14, 15, 16 and 18 and opened its contact 17. C, has also closed its working contact 19 and thereby prepared the circuit for the rotary magnet D1.

In connecting relay A, with the line (L and the Wi'ndin 2 of the relay Bl with the line these reys were excited because at the trunk line oilice the line loop a, b had been closed or because at a and b correspending potentials had been impressed. Thereupon Without interrupting the excitation of the relay B, over the line a. from the dial switch of the long distance suhserber current impulses are sent which act upon the relay A, in such a manner that this latter becomes electrically inoperative at euch current impulse, thereby closing its contact 20. As Contact 18 of Bl is closed at each current impulse the lifting nmgnct Hl Will be excited over the ground, battery, H 20, 18 and ground, said lifting magnet Il, lifting at each current impulse the switching axle of the selector IILGVVF by one step. At the tiret step the contacts Ir., and le, ofthe head switches will be opened and contact k, will be closed. After the last lifting impulse the circuit for both relays A, and B, will be interrupted until at the beginningr of the immediately succeeding series of im' pulses, by having theline loop at the trunk line oilicc closed, or by having the respective potentials impressed upon lines a. 'and l switched oli. The relay B, 'which will be switched ott' at 13 after being no more excited from the. 'strand and which remains comici-ted to the line c over 12 thereby closes the contact 17, so that now, since (l, is excited, the rotary magnet D, receives periodically interrupted current impulses over ground, battery, 19, 17, le, and thereby rotating in steps the Switching axle ol' the group selector IILGVIY'. At the first step the axle Contact ndr, will be opened and uf/c, will be closed'. By this, new. as B, is no more excited, and its contact 1G closed, the relay C, will be ciouected with both windings l and 2 over contacts 10, 1G and not, with the line c. New upon rotation of the switching axle the switching arms of the saine will malte connection with a free line Selector, for instance, LW of Fig. 3, the following circuit will be established: ground, winding 2 of 13 contact 12, line r" and c, to the line Selector LW in Fig. 3, contact 21 of relay F, winding 1. of a relay (YU head Contact tg, battery und ground. lu this circuit thc relay B, at the roup selector TUNVF and C2 at the line Selector lili" will respond. B, again will cloee its contact 16 and therewith connects its Windings 1 and 3 over 16 and 10k., to the line e, so that ll, after being excited over its windn ing 2 will now also he further kept excited f over ite windings l and 3 and line c. As

ground,

B1 by reason of the latter excitation has opened contact 16', therewith the circuit of relay C, had been interrupted, and the latter denergized, its operation now being taken up by the relay B1. This operation consists therein that the circuit for the release magnet M, ground, battery, 17, 1.9', M1, battery und ground, which circuit is closed by closing of the contact 19 of (3 will simultaneously be kept open at 17 by the relay BV The relay B, has also its` contacts QQ, 23, QJ@ and 25 closed at the eet of relays RS in Fig. 2 and therewith the testing of the deaired line has been prepared from the trunk line office. By denergizing (l,l and closingr the contact 1Q, the winding 2 of relay E will be connected to the line e' over the contact 15 which is closed by relay B1. As relay E is already excited by its Winding l being in circuit of the relay C, which had already been energized together with the latter and its contact 26 open, then altcr the Contact of the testing lcwr of the group eelector HTIVWF aud after the de`e`nergizing ot' the relay (l, also the Winding 2 of IG will be connected to thc liuc c" and therewith thc excitation of E will be further u'iuintaincd by having thc contact 2G open after the interruption of the circuit for winding 1 of E. As the contacts 2'? and 28 of relay E will remain closed after adjustnient ot' the group selector HlGlVF by having the potentials impressed upon the lines a and 7) at the long',r distance Station, the circuits for the relays A, und B, ot the liuc selector LlV will be closed over thc contacte 2T and This is lue to the fact that the relay (l, has heen excited after contacting with a free line selector and thereby closed the contacteA 29, 30, 31, 32, 33, 31 and 3G and opened the contacts 35 and 3G. By closing 29, for a retarding relay V over the Winding 1 therefore the following circuit has been established: ground, battery, 29, Winding 1 of V, axle Contact wlc and ground. In this circuit V will respond and close its contacts 37, 38 and 39. Ait 37 and 38 relays A., and il, are` connected to the lines a and and excited over ground at the trunlc line ollice, line e, 14;, 27, a", 37h11 winding 1 of A2, 34, battery, ground, or `ground at the trunk line oliice, line b, 13, 28, 11, 38, winding 1 of B2, 44 and ground. The relay Vfurther Vwill close its contacts 39 and 40 so that its winding 1 will still remain excited over 39 and the contact 41 ol B2 if wk, is opened. The relay B2 upon boing excited has closed over contact 4:2 the excitation circuit for u relay ll over ground, axle contact 'w: winding 1 of relay U, contact 42, head contact 15, battery and ground. The relay U upon being excited will close at Contact 43 the circuit for the lifting magnet H, of' the line selector LW, the circuit being ground, battery 31, H2 4?, 46, wie, and ground. Furthermore the relay U will open at 44 the circuit for the relay B2, the latter, however, remaining further excited over its contact 45. If now again a series of impulses is sent from the numeral sender of the lon distance subscriber station into the. line a, the latter by means of the relay A2 will act over contact 46 upon the lifting magnet H2. The latter now will lift the switching axle of the line selector LW by a number of steps corresponding to the given number of cur-- rent impulses. At the first Step the head contacts 7s, and 7:2, will be opened and k2 and 7e, closed. The relay C2 will remain in its working position, upon il', being opened, over its contact 33, battery and ground independently of' c, and after opening of k2 the winding 1 of the relay U will be further kept excited over its contact 47 independ ently from 711,. A

After completion of the lifting impulses for the line selector INV neither relay A2 nor B2 is excited for a. short time and they will then simultaneously release. The relay (l2 and E thereby will remain excited by the circuit over ground` battery, 33, windings 1 and 2 o'f Q2, 21, 49', 48, 32, resistance w and ground or c, c', 12 winding 2 of E, 15, ground, the resistance w being so di mensioned as to prevent the releasing of E. 'At the Contact 42 of the relay B2 the current passing through winding 1 of relay U will be interrupted. This relay becomes inoperative and therewith closes its contact 413', while 43 will be interrupted so that thereby reversing from lifting magnet H2 to rotating magnet D2 will take place.

Thereupon A2 and B2 will again be excited from the long distance subscriber station. Now, the given current impulses act also over the line c, a upon the relay A2, while relay B2 is being energized. 'These impulses will be transmitted in succession from the rel ay A2 by opening the contact 46, over con* tact 43" to the rotary magnet D2, 43', 46, wk, and ground. At thelirst step of rotation the axle contacts Mk2 and 10764 will be opened. The circuit passing over wka for the relay V and the rotary magnet D2 will thereby be interrupted, both, however, will further remain excited over the contacts 41 and 39 and ground. After completion of the current impulses for the rotation of the line selector, from the long distance subscriber station a special combination of current impulses will be sent temporarily, said combination consisting therein that the current for A2 will still be maintained for a certain while, the circuit of B2, however, being simultaneously interrupted. Accordingly contact 48 of B2 and contact 49 of A2 will be closed so that the ciic'itier the relay C2 will now be established ove ground, battery, `contacts 33, windings l and 2 of relay C2, relay F, contacts 49, 48 and 33, resistance w, ground and 21, c, c 12, E, 15 and ground. In the former circuit F will be excited and C2 will remain further excited in series with F. The relay F o ens its contact 21 and thereby switches oli' the relay E while it will prepare on the one hand by closing the contacts 21', 52 and 53 a control circuit for keeping the relay C2 and F in working position, and on the other hand establish the circumventing path P over the line d for throughcon nection. The relay F opens its contact 50 and therewith prevents a circuit for a testing relay P of the line selector from being eventually established, which circuit is otherwise closed when employing the line selector for local connections. Furthermore the relay F will open its contact 51 and therewith prevent the releasing of the line selector which will occur after relay C2 is denergized and contact 36 closed when employing the line selector for local connections.

The testing of the local subscriber line called for from the trunk line oflice Will now be done by means of a testing relay Pa and Pb of the set of relays RS. For testing three conditionspf the line called for must be distinguished; this line may be free or occupied, the latter being the case if theA subscriber called for is carrying on a local or long distance conversation. In the former case the existing connection may be separated in favor of a long distance connection, to the latter case, however, this does not apply. For each of these three conditions a separate signal, for instance, in form of diiferent buzzers must be rovided.

- The switching operations 1n testing the desired line are as follows First condition-the desired line is free: After dener izing the relay E of the group selector III. WF its contact 27 closes and the winding of the relay X. is connected over this contact with the grounded line a, this latter relay will be excited over battery, 25. 27, 14 and ground as the windings l and 3 of the relay B1 and '10162 at the group selector IILGWF and relay A2 at the line selector are still excited. The relay A2 is maintained in energized condition over the contacts 62 and 62 instead of contact 27. Relay X closes its contacts 55, 58 and 68 whereby over contact 55 a current impulse for the testing relayPa will be generated in. the circuit made over ground, Pc, 555, 6l, the fourth arm of the long distance group selector HLGWF, line d, the third arm of the line selector 'to battery and ground at the preselector of the desired subscriber. The battery at the pre-selector is disconnected, if the desired subscriber'line is occupied. The excited relay Pa opens its contact 61 and thereupon switches itself over its contact 80 into a holding circuit over ground, battery,

24, (relay B1), 65, 80, Pa. and ground. The n relay Pa furthermore connects over its contacts 61 the testing relay Pl) with the line d. This rela f will now also be excited over ground, Pb, d and battery at the pre-selector of the desired subscriber line and thereupon will maintain its excitation over its contact 65 and the contact 24 of relay B1. Upon closing contact 65 also the contact 65 will be instantly interrupted, after 65 is already closed. By the opening of contact 65 the circuit for Pa will be interrupted and therewith this relay denergized. The relay Pl further closes its contact 64 whereby line d is immediately connected to ground. By this also the holding circuit prepared over the contact 21 for the relays C and F will be closed, as their circuit upon rexciting the relay B2 at the closing of the line loop is interrupted over 4&9, 48, 32, w and ground and at the same time prevents the relays Pa., Pb of another set of relays RS or the relay P of another line selector LW from making a local connection (contact 50 of F open). The line of the desired subscriber therefore will be locked for other connections, and this for local as well as for long distance service. Relay Pb has further its contacts 66. 71 and 72 closed. Thereby the circuit for the relay L will be closed over ground, battery,L, 68, 66 and ground. Now, a circuit will be established over the working contact 57 of the relay L as follows: ground, buzzer'. Fr, 57 58, translator winding, contact 25, battery and ground. The current of the buzzer Ff' flowing in this circuit will be inductively transmitted upon the line a and over the latter to the receiver of the operator at the trunk line office. By this the operator will be notilied that the desired line is free, whereupon the desired connection may be completed. It the relay L responds over the contact 70 and 81 thereof, a calling current will be sent into the line a, b, said current flowing over contacts 7l and 72 oi? the excited relay Pb, over the line selector LWr and contacts 52, 53 of the excited relay F into the desired line, thus effecting the call for the desired subscriber. The respondin,f ,r of relay L and therewith the call of the desired subscriber may be 'nade by repeated sending of the combination of current impulses from the long distance subscriber station. It the desired subscriber thereupon answers, the line loop will be closed upon taking oft the receiver of the called subscriber over af', 7) and therewith the relay S positioned in the loop at the group selector ULGVVF will respond over 9") battery and ground. This relay will disconnect at 74 and 75 the relay X from the talking lint` and the talking connection is niade over the contact 13 and 1l at the group selector TILGWF, translator Spil at the Set of relays RS and over the contacts 52, 53 at the line selector' LW. The relays' P and U at the line selector are not excited in this case.

Second condition-the desired line is occupied by a local call: In this case after the excitation of the relay X at the set of relays RS only the testing relay Pc can respond, as in case the local subscriber which is de sired for the long distance connection has been the calling party at his pre-selector the low resistance winding ol'- a separating ielay is switched into the testin line. On the other hand, if the desired siiscriber for the long distance connection has been called for by the existing local connection, then at the line selector LW' of. the existinglocal connection the low resistance winding of the testing relay for this line selector will be switched into the testing line. The relay Pa at the set of relays RS is also ot low resistance and in being connected to the ltesting line d for the desired subscriber it obtains current suflicient to respond. The testing relay Pb is of high resistance and on being switched into the line cl over 6l will be passed by current which is not suflicient for its excitation. Consequently relay L will not respond. The excited relay Pa thus makes up the circuit for the buzzer OV at the contact 56 over ground, OV, 56', 58, 25, battery and ground, the noise of the buzzer being inductively transmitted upon the line a and over this to the receiver of the operator at the trunk line otlice. The operator, now, Will interrupt the existing local connection and then make the lon distance connection, whereupon the relay P will respond. Said relay is connected over 64 and ground to the line d so that now the holding current for the relays F and C will, be closed, therewith also the desired line will again be locked for any other connections. The excited relay C2 by keeping contact 36 open, will prevent the release magnet M2 from responding over ground, battery, M2, 36, p, cu and round, and therewith also the line selector L from being released. The excited relay F, on the other hand, by keeping the contact 51 open, will prevent the closing of a circuit of the counting relay of the inter-ru ted local connection and therewith also t e counting of this local connection having been prematurely interrupted in favor of the long distance connection.

For releasing a long distance connection which has been made over group selector 'III.GWF, set of. relays RS and line selector LW the circuits existing over a, b, c will be interrupted at the trunk line ollice. Therewith Bl at the group selector IILGWF will become inoperative and open contacts 13 and 14. Furthermore contact 17 will be closed by B1 and therewith the release magnet M, of IILGWF will be excited over ground, battery, M1, 19', 17, lo, and ground, said magnet bringing the group selector HLGWF back to its position of rest, the circuit for M, beingautomatically interrupted at k3. At the release of the group selector IILUrlVF by the magnet M, the switching arms of the saine leave the contacts leading to the Line selector LW. Thereby also the circuit for the relay C, and F over thecontact 64 and line d will be interrupted, thus rendering free the line of the subscriber called for, C, at the same time will close oi'ercontact 36 the circuit for the release magnet M., over ground, battery, M2, 36, p, le, and ground saidmagnet releasing the line selector Li As soon as this latter moves back into its position of rest at ka the circuit for M, will be automatically interrupted. Also all other switching instrumentalities which have formerly vbeen opcrated at this moment will return into their position of rest.

Third c'uiditionvmthe desired line is occupied by a long distance connection: 1n this case at the set of relays RS of the. existing long distance connection the relays Pb will be excited and its contact (il closed. The testing relays la and Pl; of the set ot' relays RS established, therefore rendering the desiredv long distance connection temporarily not possible and requiring the desired line to be called up later. i

In Fig. L in the circuit at the long distance subscriber station F a numeral senderZ is provided which is so constructed that after its adjustment first 'the current impulses for adjusting the group selectors LGW, H GW, IILGW will be generated and thereupon also the current impulses for adjusting the limJ selector LN, which like the aforesaid group selector. are inserted into the preliminary conditions whereby, however, the test ing and all succeeding switching procedures will be suppressed by the adjustment of the line selector LlV for ordinary local connections. From the dial switch by means of a fannbination of current impulses, which can only be made at I", a call seeker AS will thereupon be energized thc way back to the trunk liuc otlicc (circuuivcnting connection) owinAS being. however. different from that by which the desired line has been reached. Thereupon by #be numeral sender the our* rent impulses for adjusting the selectors for the cireumventing connection are also given aiitomatically without any manual steps on current impulses for adjusted numbers for the selectors of the circumventing connection such as, for instance, those which correspond to the number of the long distance subscriber line. The operator, now, makes the long distance connection over line see lector LlV call seeker AS and line selector LW the connection over LGW rIl GrlV; 1l IGlV being at the same time released.

` For exciting the call seekers AS the same combination of impulses may be u `ed as for adjusting the line selector LW, said combination exist-ing during the excitation of the relay A, the relay B2 being at the saine time inoperative, as shown in Fig. 1a.

Thereby the circuit for the starting relay An. 15 lf2, a?, and ground is closed over a working contact a2 of the relay A, and a back contact 7);, of the relay B2. It, there fore, thccontacts a2, b2 are simultaneously closed, then the relay An and the relay E4 ,insei-ted in the same circuit will be excited. The` rel ay An closes over its working Contact rn, the circuit for a relay R belonging to a free call seeker, this circuit being made from ground, battery, Aman, R, p2 and grcaind,` while a holding circuit for A and E will be formed over the Working Contact e of the relay E, as follows: round, t1, 6,. Fn, An, battery and ground. ver the working contact r, of the relay R, the circuit` 'for the rotary magnet will be closed over ground, battery, interruptor, rl, D, 10 and ground, causing the switching levers of the call seeker to rotate until itwill contact ywith the respective line. In this nstantvthe test relay P will'respond over the lever for the test switch and the c-strand. a circuit being formed over ground. batteryjrZ, P, T, e, and ground, said test relay short-circuiting its high resistance winding over its working contact 77 whereby the separating relay T will respond; a circuit being formed over ground, battery, 77 l), T, c, and ground.

At the saine time the line will be throughnested at p3. Thereby the call seeker AS .will be brought to rest.

In Fig. 5 the circumrenting connection, forming a new path according to this in vention is shown. which in contradiction to well known arrangements. leads to a different place of the preliminarir connection than that from which the long distance connection is prepared. rllius the new connections made may lead to special places such as Fl) in Fig. (i which are arranged separately from the places with which the numeral sudcrs Z are associated. These FP places as shown in Fig. i may he positioned in the same room with the places of the numeral senders, or they may also be installed in other rooms or buildings. Conversation between these places for the numeral senders with the F-places mav be carried on over oliice lines provided especially for this purpose or in any otherdesired manner.

In Fig. 6 an arrangement is shown, whereby it is assumed that a B-place for the numeral senders is provided in common for Several long distance places FI each i containing a, jack for an operators cord as shown in Fig. 4.A From the numeral sender B. in order'to connectl with the desired local subscriber T, a connection may be made over preselectors VWK, VVZ, IHV. II.GW, IIIGVF, said selectors belonging all to the trunk line office, and over the line selector LW serving also for the local connections and therefore belonging to the local oiiice. A setof relays RS, Fig. 2. is again associated with the selector IIIGVVF. After the aforesaid selectors have been adjusted upon the desired. line, a new way, namelyY the circumventing connection Will be established over the call seeker AS and a special selector IJWl for long distance places FP. This connection. i'or instance, may be made over AS and LW, by sending after the adjustment of the selectors VWI, VW... IGVV, ILGVV, IILGVVF and LW a current impulse from the B-place over the line of these selectors.` said current exciting the call seekers AS for adjustment upon this line. Now,V after the operator at the B-place has found a l'ree long distance subscriber line, for instance over special oliiee lines or the like. from the B-plaee through the numeral sender located at this place eurl rent impulses will be sent to the. selector LVVI, said impulses adjusting said selector upon said found free long distance subscriber line. Thereupon the pre-selectors and group selectors may be released so that the long distance call proper is accomplished only over one long distance place F, selectors LVV, seekers AS and subscriber' selector LW, while the other selectors become free for preparingother long distance connections. By such arrangement with separate places for impulse signaling and long distance places a great saving is obtained in the number of numeral senders.

In Fig. 7 I have shown a connection .if a B-plaee over the selector IGIV, I LGW, IIIGW'F with subscribers 'l of a local` of` tice, in which preselectors VW are associated with the subscriber lines. From these free selectors lines in multiple conv nection are led over one or more switches AS to the trunk line oiiice. If, now, a connection is existing between one Vof the subscribers T with another subscriber of the local ollice, and if to this existing local consubscriber designated with Sp and corre-` spending to the subscriber T of Fig.V 7 contains besides the testing or separating relay T and the call relay R a resistance w and a special switchin arm a'. With the con# tacts of the prese eetor a number of lines are connected in the usual manner leading to the local ellice. Those contacts of the preselector VIV which correspond at the switching arm al tothe connecting contacts of the lines leading to the local .#iilirze., are connected with one another and the connecting line c originating from this common connection of the contacts is used as a testing line back to the Bplaee. The connection of this place with the desired subscriber station Sp mayT also be estab* lished over pre-selectors, group selectors and a line selector LW, such selectors being shown at LGW, IIGVV, IIIGIVF and LW in Fig. 8 of the drawings. 'For this purpose at the B-place after havin made the connection to the desired subscriber station Sp, the release of the selectors of this existing local connection is effected in the manner above described for Figs. 2 and 3 Without, however, releasin the selector VW. In this case the relay of the pre-selector VW by impressing proper potentials upon the line o, b at the B-place will be kept excited, while the relay T oi the pre-selector VNV will be temporarily short-circoited by impressing a proper potential (ground) upon the line c at the B-place, and therewith made inoperative. By this the rotary magnet D of the pre-selector VW will be excited over ground, battery, D, r, t) and ground, said magnet rotating the switch 1evers of VW until the relay T will respond again and interrupt4 the circuit of the ro tary magnet at t. and that of relay R at t2 and 11.., that is to say, as soon as the testing switch of the pre-selector VW contacts Ywith a line feeding to the trunk line oliiee F.

The grounding of a line leading to the trunk line oiico is made at the long distance pglace F which is noted by the operator at the place as being free and which is destined for the desired long distance connection.

In order to again disconnect a long distance connection according to the arrangement of F ig. 8, the relay T which has switched ofi' the relay R ot' the pre-selector4 10 VlV is made inoperative, whereupon relay T will again connect said relay R to the line and the selector will be brought into its position of rest as R switches the magnet l) into circuit.

In F ig. 9 ll have shown a scheine for long distance connections with local subscribers T, whose lines are connected at the local office with call seeker contacts and led over first and second call seekers LAS'and 2.AS,

instead of being connected to the pre-selector as shown in Fig. 8. The connections of some of the second call seekers 2.AS lead to the trunk line office F, while the connections of the other second call seekers c.AS are connected to the local office O.

By means of call seekers A53, as shown in Fig. 10, the connection to the local subscribers is accomplished from the long distance subscriber station of the trunk line oice F. For making a connection from a B-place with the local connection, only the B-place and a subscriber selector LW is indicated. The subscriber selector LW corresponds t LW of Fig. 3. These connections are made in the above described manner for the arrangement according to Figs. 2 and 3. In order to disconnect the existing local connection 'in favor of the desired long distance connection the operator of the B-place 40 again impresses proper potentials upon the line a and b. Besides at the B-place the c-line will be temporarily connected to the battery by nieans of the key te. Accordingly the relays A3 and Pswill respond, a circuit being formed over ground, batte? fc, t4', P3, A3 and ground. The relay 3 which will be excited thereby, now connects over its contact p3' the relay T3 to the testing contacts of the call seeker ASa over a 50. circuit foi-ined by ground, battery, p3, T3, 151 Vwnmw Cm fm, and ound. The relay A3 switches the relay R3 of the call seeker A33 into circuit over ground, battery, am R3, o, and ground, which thereupon switches the rotary magnet D3 of the call seeker AS3 into ircuit, a circuit being formed over ground, interrupt-er, D3, o2', r3, as, battery and ground. The arms of the call seeker A S, are thereby rotated until they contact with the line to the relay '11,. Thereupon the rclays T3, V2, and C3 are excited. V2 interrupts at t4, t4 the circuit of P3 and Ag which latter will denergize the relay R.s at 0.,. Furthermore Td will close over its Working contact tu a holding circuit of its own, this circuit being formed over ground, battery Pf, tg, V2, m3, G3, w1 andground. in this circuit the low resistance relay P4 will not respond and relays T V, and will be further kept excited.

It', however, at the long distance silbscriber station which has been found free by the operator of the B-place and which has been notified by the operator of the d esired long distance connection, the key t will be depressed and therewith a resistance 'wi inserted in the circuit of V2, T3 and P4 will be short-circuited, then also P4 will obtain sullicient current for responding. P, then opens at 7J, the circuit for the relay T2 at 80 the call seeker AS1, V1 at thecall seeker ASQ and C at the first group selector at the local oflice (l. By this, now, tliesclector of the existing local connection will be released, at the same time the call seeker AS2 85 will be made free. Furthermore P, will close the contact p5 over whidh the excitation of the relay T1 of the call seeker AS,I which relay T1 is excited during the existing local connection, will be further kept excited without any interruption. so that now the call seeker AS1 will also be operated for a long distance connection which has just been established.

The relay '11, when responding, will keep 95 open the circuit for the rotary magnet D1 of the call seeker AS1 by means of the contact t4, so that if I), responds by opening contact p, which causes the relays T2 and V, and C to be denergized by closingthe contact t2 of the relay T2, the call seeker AS1 will therefore be prevented from being further rotated.

In order to disconnect this long distance connection, the circuit for Tj, will be interrnptcd at the trunk line ofiicc. for instance by depressing a key my whereby the relays (1,. TR, l), and T, will be inadc inoperative and the seekers AS, and AS1, again be ready for making new connections. Y A

Haring thus dccribcd my invention I claim as new and desire to secure by Letters Patent of the United States 1. Iii a telephone exchange syslcin, subA sci'ibei's lines, switches for establishing a 115 preliminary connection between a calling line and a called line, other switches for establishing a talking connection between said calling and said called line, impulse generating means for controlling said first switches, other impulse generating means for controlling said second switches, said second impulse generating means being a1'- ranged to send impulses in addition t0 the impulses of said fi"st impulse generating ine-ans.

2. In a telephone exchange system, subscribers lines, switches for establishing a` preliminary connection between a calling line and a called line, other switches for establishing a talking connection between said calling and said called line, impulse generating means for controlling said rst switches, other impulse generating means for controlling said second switches, said second impulse generating means being arc ranged to send impulses in addition to the impulses of said first impulse generating means, both said impulse generating means being components of one apparatus.

3. In a telephone exchange system, subscribers lines, switchesfo'r establishing a preliminary connection between a calling and a called line, other switches for establishing a talking connection between said calling and said called line, manually adjustable impulse generating devices for controlling said first switches. another impulse generating device associated with said preliminary connectiony and automatically sending out impulses for controlling said second switches.

4. ln a telephone exchange system, subscribers lines, trunk lines less numerous than said subscribers lines, switches for establishing a preliminary connection with one of said subscribers lines, other switches for establishing 1a talking connection with said desired line, impulse generating devices for controlling said first switches, another impulse generating device for controlling said second switches, said talking connection being branched oli' from one of said trunk lines, said second impulse generating device being associated with said preliminary connection.

5. In a telephone exchange system, subscribers lines for ordinary' and preferred service, calling stations for preferred service, switches for establishing connections for ordinary service, means for establishing a preliminary connection with one of said subscribers lines over said switches for ordinary service, other switches for establishing a preferred .connection between said one of said subscribers lines and one of said preferred calling stations.

6. In a telephone exchange system, subscribers lines for ordinary and preferred service, calling stations for preferred service, switches for establishing connections for ordinary service, means for establishing a preliminary connection with one of said subscribers lines over said switches for ordinary service, other switches for establishing a preferred connection between said one of said subscribers lines and one of said preferred calling stations, and an impulse generating device for controlling said preliminary and said preferred connections, said impulse generating device being associated with said preliminary connection.

7. In a telephone exchange system, subscribers lines, switches for establishing ordinary and preferred connections between Isaid subscribers lines, impulse generating devices for establishing a preliminary connection with a desired one of said subscribers' lines over said switches for establishing ordinary connections, and other impulse generating means controlling said switches for preferred connections, said other impulse generating means being arranged to send impulses in addition to the impulses of said first impulse generating device.

8. In a telephone exchange system, subscribers lines, switches for establishing preliminary connections with said subscribers lines, other switches for establishing a talking connection with said subscribers lines, impulse generating devices for controlling said first switches, other impulse generating means controlling said second switches, said other impulse generating means being 85 arranged to .send impulses in addition to the impulses of said first impulse generating device, circuits for releasing said preliminary connections, and other circuits for releasing said talking connections.

9. In a telephone exchange system, subscribers lines, switches for establishing ordinary and preferred connections between said subscribers lines, impulse generating devices for establishing said rdinary connections over contacts of saidswitches, and other impulse generating means sending impulses in addition to the impulses of said first impulse generating device for establishing said preferred connections over 100 other contacts of said switches.

l0. In a telephone exchange system, sub-- scribers lines, switches for establishing ordinary connections between said lines, operators places for establishing preferred connections with said lines, said preferred connections being preceded by a preliminary connection with said lines, an impulse generating device for establishing said preliminary connection, and another impulse gen 110 erating device sending impulses in addition to theimpulses of said first impulse generating device for establishing said preferred connection.

1l. In a telephone exchange system, sub- 115- scribers? lines, switches for establishing ordinary connections between said lines, operators places `for establishing preferred connections Vwith vsaid lines, said preferred' connections being preceded by a preliminary connection with said lines, an impulse generating devic'c' for establishing said preliminary connection over said switches provided for said ordinary connections, and another impulse generating device sending impulses in `addition to the impulses of said first impulse generating device for establishing said preferred connection.

12. In a telephone exchange system with calling stations for ordinary andpreferred devices service, the combination of subscriber selectors for preferred service, instrumentalities for making a preliminary connection with such subscriber selector, selecting means permitting a back-selecting from a line of this preliminary connection, preferred service erator of additional impulses for operatin said devices from the calling station, an reserving means fory engaging the subscriber selector.

13. In a telephone exchange system for ordinary and preferred service, the combination of subscriber lines, with subscriber selectors for preferred service, instrumentalities for making a preliminary connection with such subscriber selector, means permitting back-selecting from a line of this p reliminary connection said means consisting of a selector controiled from a calling station; subscriber selectors for making connections vvith said subscriber lines, special selectors for establishing preferred connections with the subscriber selectors, and controlln devices for preferred service, said contro ling devices being associated with said selectors.

14. In a telephone exchange system for ordinary and preferred service, the combination of subscriber selectors, with subscriber lines and exchanges, instrumentalities for making a reliminary connection with a subscriber se ector in case of referred service, means ermittingaback-se ecting from aline of sai preliminary connection, said means consisting of a selector controlled by a preferred subscriber when calling, and apparatus for making the talking connection, said apparatus bein associated with the selector for preferre service.

15. In a telephone exchange system for ordinary and preferred service, the combination ^f subscriber stations, with subscriber select s, circuits for making preliminary connections with such subscriber selector iii case of preferred service, selectingmeans and controlling means therefor actuated from a subscriber station for preferred calls and permitting back-selecting from a line 0f this preliminary connection, subscriber selectors for ordinary connections, special controlling device therefor, second selectors associated with the former for establishing connections with subscriber selectors for preh ferred calls, and special circuits for operating said second selectors, said circuits being separate from the circuit for the ordinary connections.

16. In a telephone exchange system for ordinary and preferred service, the combination of subscriber stations, with subscriber selectors, switching instrumentalities for long distance service, talking Wires, means for making preliminary connection with a subscriber selector in case of preferred servfo such subscriber selector, a gen ice, selecting means permitting back-selecting from a line of this preliminary connection and controlling means therefor actuated from a calling station, means for connecting said switching instrumentalities to the talking wires, and a special impulse generator for connection over said talking wires after completion of saidl preliminary connection.

17. In a telephone exchange system for ordinary and referred service, the combination of su scriber stations, with subscriber selectors, switching instrumentalities for long distance service, talking wires, means for making preliminary connection with a subscriber selector in case of preferred service, selecting means permitting back-selecting from a line of this preliminary connection and controlling means therefor actuated from a calling station, means for connecting said switching instrumentalitis to said talking wires, a special impulse generator for connection over said- Wires aftercompletion of said preliminary connection, and means forthrough-connecting and clearing out the talking line.

18. In a telephone exchange system for ordinary and preferred lservice, the combi` nation of subscriber selectors, stations and lines, with instrumentalities for making a preliminary connection with a subscriber selector in case of preferred service, selecting means and controlling means therefor actuated from a station for making a preferred call and permitting back-selecting from a line of this preliminary connection, subscriber selectors for makin ordinary connections with the subscriber lines, special controlling devices for long distance service, and a relay provided at the subscriber selector for through-connecting the talking line by a special circuit in case of preferred connections.

19. In a telephone exchange system for ordinary and preferred service, the combination of subscriber selectors, lines and stations with instrumentalities for making a preliminary connection with a subscriber selector for preferred service, means permitting a back-selecting from a line of this preliminary/connection, means for 'sending a controlling impulse from a calling station to a subscriber selector, and further means for transmitting said impulse backwardly upon the means for back-selecting.

20. In a telephone exchange system for ordinary and preferred service, the combination of subscriber selectors, lines and stations With controlling devices for referred service connections, instrumentalities for making a preliminary connection with a subscriber selector in case of preferred service, means permitting a back-selecting from a line of said preliminary connection said means consisting of a selector controlled from a preferred calling line, switching instrumentalities for making the talking connection, a controlling device for preferred service associated therewith, means for sending a controlling impulse from the preferred calling station to the subscriber selector, and further means for transmitting said impulse b ack upon the selector of the back connection;

21. In a telephone exchange syste-m for ordinary and preferred service, the combination of subscriber selectors, with special switching devices therefor, subscriber lines and station and circumventing lines, operators places, subscriber selectors for preferr-ed service, instrumentalities for making a preliminary connection with a subscriber selector for preferred service, means permitting a back-selecting from a line of this preliminary connection, said means consisting of a selector and controlling means therefor actuated from an operators place, second subscriber selectors for making ordinary connections with the subscriber lines, special controlling devices therefor, special circuits for operating said cond selectors separate from the circuits for the ordinary connections, and a current impulse generating device adapted to be operated by a preferred calling station, said generating device being capable of giving automatic current impulses for adjusting the selectors of the preparatory connection and for causing the special switching devices to coperate with said second subscriber selectors and for adjusting thereupon also the selectors of the circumventing connection.

22. In a telephone exchange system for ordinary and preferred service, the combination. of subscriber selectors, with special switching devices therefor, subscriber stations, connecting lines, and talking wires,

`means for making preliminary connection with a subscriber selector in case of preferred service, selectin means permitting back-selecting from a ine of this preliminarg7 connection and controlling means therefor actuated from the calling station, switching apparatus for lon distance service, connections between sai apparatus and the talking wires, so as to make said wires operatively inserted after completion of a preliminary connection by a proper current impulse from the calling line, means for through-connecting and clearing out thev talkingwire, and a currentimpulse generating device adapted to be operated by a preferred calling station, said generating device being capable of giving automatic current impulses for adjusting the selectors of the preparatory connection and for causing said special switching devices to coperate with said subscriber selectors and for adjusting thereupon the selectors of the circumventing connection.` i

23. In a telephone exchange system for-ordinary and preferred service the combination of subscriber selectors, subscriber lines, instrumentalities for making a preliminary connection with a subscriber selector in case of preferred service, selecting means and controlling means therefor actuated from the preferred calling line and permitting bac -selectin from a line of this preliminary connection, special controlling devices, a relay provided at each of the subscriber selectors for through-connecting the talkin line by a special circuit in case of preferre connection, and a current impulse generating device adapted to be operated by a preferred calling station, said generating des vice being capable of giving automatic current impulses for adjusting the selectors of the preparatory connection and for causing the special controlling devices to coperate with said subscriber selectors and for adjusting thereupon also the selectors of the circumventing connection.

24. In a telephone exchange system for ordinary and preferred service, the combination of subscriber stations and lines and trunk lines with subscriber selectors'for ordinary connections, special controlling devices therefor, operators places, instrumentalities for makin a preliminary connection with a subscrier selector for preferred service, means permitting a back-selecting from a line of this preliminary connection, said means consisting of a selector and a controlling device therefor actuated from an operators place, special circuits for operating said se ectors separate from the circuits for the ordinary connections and a current impulse generating device adapted to make automatically a circular back-connection at a calling station, switching devices for connecting the lines which originate from said calling station, and separate switching devices for the incoming lines at the station thereof for connecting the same with the trunk lines.

25. In a telephone exchange stem for ordinary and preferred service t e combination of trunk lines, talking wires, subscriber stations, with vlines and selectors, means for making preliminary connection with a subscriber selector in case of preferred service, selecting means permitting back-selecting from a line of said preliminary connection and controlling means therefor actuated from the calling and, switching instrumentalities for long distance service connected to the' talking wires so as to make said wires operatively inserted after completion of a preliminary connection by a special current impulse from the `callin line, means for throu h-connecting and c caring out the talkin wire, and a carrent impulse generating evice capable of making automatically a back-connection at a calling station, switching devices for connecting the lines which originate from said subscr1ber calling station, and separate switching devices for the incoming lines at the end thereof for connecting the same with the trunk lines.

26. In a telephone exchange system for ordinary and preferred service, the combination of local or long distance lines and stations, with special B-places provided in addition to said stations, subscriber selec tors, instrumentalities for preferred service capable of making preliminary connection with one of said subscriber selectors, means permitting back-selecting from a line of this preliminary connection, lines for engaging the subscriber selectors which originate from said B-places and lead to the selectors for the local connections, and lines for making the talking connections ending at said long distance stations themselves.

27. In a telephone exchange system for ordinary and preferred service, the combination of local and long distance lines and stations, with special B-places provided in addition to said stations, subscriber selectors, operators places, instrumentalities for makin a preliminary connection with a subscri r selector for preferred service, selecting means permitting a back-selecting from a line of this preliminar connection and controlling means there or actuated from an operators place, lines for engaging the subscriber selectors, said lines originating from said B-places and leading to the se ectors for the local connections, and other lines for making the talking connections endn at said long distance stations.

28. n a telephone exchange system for ordinary and preferred service, the combination of a trunk line oflice, with subscriber stations, special B-places provided in additin to said Stations, subscriber selectors, instrumentalities for preferred service adapted to make preliminary connection with a subscriber selector, means permitting a backselecting from a line of this preliminary connection, said subscriber selectors being adjustable over lines originating from said B-place upon contacts of the line leading to a desired station, connections between the subscriber selectors and the'trunk line office for the purpose of circumventing switching 4procedures following the adjustment of the subscriber selector. k

29. In a telephone exchangeV system for ordinary and preferred service, the combination of a trunk line oilice with subscriber stations, special B-places provided in addition to said stations, subscriber selectors, opcrators places, instrumentalities for making a reliminary connection with a subscriber se ector for preferred service, selecting means permitting a back-selecting from a line of this preliminary connection and controllable from one of said operators places, said subscriber selectors being adjustable over the lines originating from the B-place upon contacts of the line leading to the de sired station, and connections between th'e aforesaid subscriber selectors and the trunk line oice for the purpose of circumventing switching procedures following the adjustment of the subscriber selector.

30. In a telephone exchange s stem for ordinary and preferred service, t e combination of subscriber stations and lines, with special B-places provided in addition to said stations, subscriber selectors, instrumentalities for makin a preliminary connection with a subscriber selector for preferred service, means permitting a backselectin from a line of this preliminary connection, said means consisting of a selector controlled from an operators place, special controlling devices for the subscriber selectors making ordinary connections with the subscriber lines, separate circuits for operating said selectors, said subscriber selectors being adjustable over the lines originating from the B-places upon the contarts of the line leading to the desired subscriber station, and connecticns between the subscriber selectors and the trunk line oil-ice for the purpose of switching procedures following the adjustment of the subscriber selectors.

31. In a telephone exchange system for ordinary and preferred service, the combination of a trunk line oflice, with subscriber lines and selectors, instrumentalities for preferred service adapted to establish a preliminary circuit with a subscriber selector, means permittin a back-selecting from a line of this preliminary connection, a preselector and controlling means therefor actu-` ated by said preliminary circuit, a special contact for establishing the talking connection between the desired line and the trunk line ofiice, and means for adjusting said pre-selector upon said contact.

32. In a telephone exchange system for ordinary and preferred service, the combination of subscriber lines, with subscriber selectors, operators places, a trunk line oiiice, instrumentalities for establishin a preliminary circuit with a subscriber se ector for preferred service, selecting means permitting a back-selecting from a line of this preliminary connection and controlling means therefor actuated from an operators place, a pre-selector controllable by the aforesaid preliminary circuit, a special contact for establishing the talking connection between the desired line and the trunk line office, and means for adjusting said preselector upon said contact.

33. In a telephone exchange system for :rdinary and preferred, service, the combination of subscriber lines, with subscriber selectors, operators places, a trunk line office. instrumentalities for making a preliminary connection with a subscriber selector for preferred service, means permitting a back-selecting from a line of this pr8limnary connection, said means consisting of a selector and controlling means therefor actuated from an voperai'iors place, special controlling devices for said subscriber selectors making ordinary connections with-the subscriber lines, and separate circuits for oplerating said selectors, a pre-selector contro ed by t e aforesaid preliminary circuit, a spe cial contact for establishing the talkin connection between the desired line an the trunk line ofiice, and means for adjusting said pre-selector upon said contact.

84,. In a telephone exchange system for ordinary and preferred service, the combination of subscriber lines, with subscriber selectors, a trunk line oiiice, instrumentalities for making a preliminary connection with a subscriber selector in case of preferred serv-.Yv

ice/means permitting a back-selecting from a line of said preliminary connection, said means consistin of a selector and controlling means there or actuated from a preferred line, switching means for making the talking connection, a controlling devlce for the connection for referred service associated with said switc lng means, a pre-selector controllable by the aforesaid preliminary circuit, a special contactfor establishin the talking connection between the desire line and the trunk line oiiice, and means for adjusting said pre-selector upon Said contact.

35. In a telephone exchange system for ordinary and preferred service, Athe comb1- nation of a trunk line office, with sub' scriber lines and selectors, preferred service connections capable of making a preliminaryL circuit with'a subscriber selector, means pel;- mitting a back-selecting from a line of this prelimmary circuit, first, second, third, and subsequent selectors, said first selectors being controlled from said preferred service connections, said second, third, and subseuent selectors being controlled from said Erst selectors for subsequent connection with the trunk line oflice, said first selectors being in series with said second, third and subsequent selectors.

36. In a telephone exchange system for ordinary and preferred service, lthe combination of a trunk line office, with subscriber lines, subscriber selectors, referred service connections capable of making a preliminary circuit with a subscriberselector, means permitting a back-selecting ,froma line of this preliminary circuit, said means consisting of a selector controlled from said trunk line ollice, special conti olling devices for the sub- 1tion of circuits for ordinary and preferred connections, with subscriber selectors, instrumentalities capable of making preliminary connection with a subscriber selectofor preferred service, means permitting a back-selecting from a line of this prelminary connection, special Vsecond electors, one of s aid special second selectors controlled from' the circuit for preferred connections and over the subscriber selector at the timel engaged, means for paralleling another of said special second `selecto to the fo'rmer special second selector at a time in operation, and means for releasing only said other special second selector and the selectors4 back thereof in case of a subsequent separation of the ordinary connection.

38. In a telephone exchange system for ordinary and preferred service, the combination of an operators place, with subscriber lines and selectors, circuitsfor ordinary oonneetions, instrumentalities for making a preliminary `connection with a subscriber selector, for preferred service, means permitting a back-selecting from a line of this preliminary connection, said means consisting of a. selector and controlling means therefor actuated from said operators lace, special controlling devices for subscri er selectors forordinary connections 'with the subscriberi lines, special circuits for operating said selectors separate from the circuitsV for the Ordinar connections, special second"selec tors an means for paralleling one of said special' second selectors to another of said special second selectors at the time in operatlon, and means for releasing only said parallel special second selector and the selectors bark thereof in case of a subsequent separation of the ordinary connection.

39. In a telephone exchange system for ordinary and preferred service, the combination of subscriber lines and selectors, with circuits for ordinary and preferred connections, instrumentalities for making a preliminary connection with a 'subscriberr selector in casetof` preferredv service, means permitting aback-selectng from a line of saidY prelimin ry connection, said means consistln of a selector controlled from a preferred callinig line, switching instrumentalities for making the talking connection, a

fomrolling device aociated with said switching instrumentalties for preferred connection, a. 'special second Selector controlled from the circuit for referred con nections and over the subscr r selector at the time engaged, another-special second selector, means for parallelng the other specia second selector to the former special second selector at the time in operation, and

i0 means for releasing only said other special second selector and the Selectors beck thereof in case of a subsequent separation of the ordinary connection.

In witness whereof I have hereunto sei;` my signature in the presence of two suh-1 scribng witnesses.

GEORG GRABE. Witnees:

WOLDEMAR HAUPT, Hnfrwm O. NEUBAUER.

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