US1670252A - Automatic telephone system - Google Patents

Description

May 15, 1928. 1,670,252

, J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM Filed 22. 3 Sheet est 1 Inuan' In? E rdner May 192s,

, Q 1,670,252 J. E. GARDNER AUTOMATIC TELEPHONE S'YSTEM J. E/GARDNER AUTOMATIC TELEPHONE SYSTEM Filed t. 22, 1920 :5 Sheets-Sheet 3 -I1Uan U1" Patented May 15, 1928.

1 STATES idI-I'N mma, OF CHICAGO, gnnnvors,

Assienonj BY Mns'NE ASSIFGNMENTS, r0

ls n roflk riontnd'rnic Ind, 10F ciiicnoo, ILL INOISyA CORPORATION '01 DELA- WARE.

AUTOMATIC TELEPHONE SYSTEIVI.

Application filed'September 2 2, 192 0. Serial No. 412,077.

, Generally my invention relates to a telephone system in which connections are established, by subscribers without the intervention of anoperator, by the use of automatic switches. p H H More specifically my invention relates to a system comprising a plurality of main exchanges having branch ofiicessubsidiary to them, wherein after aconnection has been established from a calling subscriber in amain exchange to a called subscriber in-a branch exchange the saidcalled subscriber may, by Opratingh-is calling device pass or transfer the call to a second subscriber, such passing or transferring of a call from one subscriber tojanother continuing as long as necessary. While hitherto systems have been invented wherein the result stated has been accomplished, all of these were expensive, hard to Ina'int'ain and more or less unsatisfactory. Herein I have provided an improved and highly efiicient system which operates in a novel and very satisfactory manner.

One of the important features of my invention, is the provision of means whereby the called 'party may transfer the call to' another subscriber in the same exchange by using a simple and efficient finder switch, interlinked with the incoming selector in a large system, and the incoming connector in a, system of limited capacity, such as 100 lines. By the provisionofthese finder switches, the incoming selectors or connectors, as the case maybe, are rendered operable under control of called subscribers to pass or transfer calls to other called subs'cribers .as many. times as is necessary, or desirable; the desired result is thus accon1- 'plished in an efficient and practical manner.

This system can be enlarged to any desired size simply by inserting selectors of any standard type between the selector, inter linked with my improved finder switch, and the connector, thus making a passing call scheme quite practical in a, large or small enchange varying from 100 to 1000 subscribersor more. I have also provided means whereby it only an ordinary call is made and 'no passing. is attempted the finder switch andother additional apparatus will remain inoperative. These and other objects and features of my invention will appear tu l'ly hcleinatter.

Referring now to the drawings: In Fig. 1, 1 have shown a trunk linel and 2, terminatingin aselcctor switch E, ot the well known Keith Erickson two wire,

type, which has been modified according to the ieaturesoi my invention. At G is shown my improved finder switch interlinked with the selector E. This finder is adapted to hunt for a line in a group of 100 and to this end is provided with a vertical bank of ten contacts, one for each level, and a second private bank adapted to be enga ged by a rotarytest wiper. The selector switch engaged by two vertical wipers so con s'tructedthateach will be controlled directly by theoperat on of its corresponding switch shaft ve'rtic'ally, but will not be affected by its rotation. The vertical wiper may be attached to the cup spring case of anyStrowger switch, as shown in 3. At 138, 189 and 1-10 I have shown a multiple of the trunk line comprising conductors 1 and 2 which ,goes to multiple bank contacts in the local branch exchange first selectors and wnich is used for outgoing calls from the local ex; change overthe trunk line land 2.

t In F 2, I have shown a co'nnector switch of a standard two wire type modified to adapt it to operate in my improved system and which is accessible in common with a number of other similar connector switches to selectorsoneof which is shown at I Thefsystel'n shown in Figs. land 2 is adapted to operate in a 1000 line branch exchange, but can be readily enlarged to any capacity by inserting selector switches betweenvthe slectorE and connector H as indicated before. r

Fig. 4, shows a modification of my improved system which isa'da pted: to operate in a small branch exchange of not over 100 lines and consists of a finder switch N simi-v lar to that shown at G, interlinked with a connector L, which is very similar tothat shown at H. The Samenumber of banks,

The vertical banks of i each exchange having multipled in the same manner, as those of the selector E and finder G, are used in this system as shown in Fig. 4c.

\Vhile in the drawings I have shown a plurality of batteries it will be understood that there is preferably but one battery for its positive pole grounded.

I will now describe the operation of my system when a subscriber at the main exchange calls a subscriber in the branch exchange.

The operation of the switches in the main exchange is well known. being shown in Fig. 1 of United St ates Letters Patent to Talbot G. Martin 1.136.912 granted April 20, 1915, and hence it will be unnecessary to describe their operation except in a very general way.

Upon the calling subscriber in the main eschangc seizing the trunk line 1. 2 by means of a selector repeater (not shown) in the main exchange, a circuit is closed at the repeater for the line relay 6 over the conductors l and 2 in series. Relay 6 attracts its armature and closes the circuit of the slow release relay 7, which operates to prepare the vertical magnet circuit at springs 13 and 14 in the well known manner, and also places ground on the release trunk 1339 extending to the banks of the local first selectors to prevent; the trunk line 1. 2 being seized for an outgoing call. \Vhen the calling subscriber dials the next digit of the desired number the line relay 6 operates in response thereto in the usual manner and at each retraction of its armature 15 completes a circuit for the vertical magnet 16 in series with slow acting relay 8. The vertical magnet 16 operates to step the shaft carrying the wipers 31 to 35 inclusive to the desired level of bank contacts in which terminate the trunk line conductors 36. 37, and 38 leading to the connector H (Fig. The wiper 34: is the vertical wiper hereinbelore described and is adapted to engage vertical contacts such as =16. and other similar contacts. Upon the first vertical step of the shaft. all normal springs 22. 26 and 28 are closed and a circuit is completed from. ground G. upper armature and make contact ol relay 7. conductor 19. armature 20 and its make contact. conductor 21. oft normal springs 22. relay 9 to battery. Relay 9 attracts its armature and locks itself over a circuit from ground G make contact and armature 23 of relay 9, break springs 24 of rotary magnet 17 thence over the previous ly traced circuit, relay 9 to battery. An instant after the impulses to the vertical magnet have ceased relay 8 retracts its armature and thereby completes a circuit from ground G armature and make contact of relay 7, conductor 19. armature 20 and its break contact. armature 25 and its make contact, rotary magnet 17 to battery. The rotary magnet 17 operates to rotate the wipers 31, 32,

3-3 and onto the first set of bank contacts in the selected level, and to open the locking circuit of relay 9, which deenergizes. The further operation oi this selector depends on whether or not the first trunk is busy or idle. If it is busy a ground will be present on the bank contact engaged by wiper 32, whereupon a circuit will be completed from the said ground by way of wiper 32, conductor .29, arn'iature of relay 5 and its break contact conductor 3!), armature 24-, oil normal springs 22 relay 9 to battery; relay 9 Operates to again complete the rotary magnet circuit. This alternate operation of rotary magnet 17 and relay 9 will continue until an idle trunk is found which is designated by the numerals 36, 37 and 3S. \Vhen this occurs there being no ground present on the bank contact engaged by wipei" 32, relay 5 is no longer shorted out as was hitherto the case and will energize in series with relay 9 in the usual manner, relay 9 remaining inoperative on account the relative rcsistances of the two relays. Relay 5', however. attracts its armatures and extends the trunk conductors 1. and 2 to the line relay 95 ot the connector l-l (Fig. 2). It will be seen that relays 11 aud ll arev included in series with the energizing circuit of relay Relay 12 will energize but relay .11 is apolarized differential relay and its local circuit. cxten ding from ground G, conductor 19. arn'iature l9, conductor 11. resistance 42, lower winding of relay 11 to battery is completed at the same time as the circuit for its upper winding; therefore this relay will remain inoperative during dial impulses and until battery is reversed over the trunk conductors 36 and 38. Relay 12 however will operate in response to any impulses sent to the line relay 95-ot connector H. but its operation will have no effect at; this time. It. will be seen that condensers 42) and 44- are shunted across each oi the relays 11 and 12 and thus the tansmission of voice currents will be unaffected by the inclusion oi these low resistance relays in the line circuit.

Returning now to the operation of the connector H, when the next digit of the called number is dialled the line relay 95 operates in the usual manne' and at each retraction of its armature completes the vertical magnet circuit from ground. break springs of relay 95, armature. and its make contact. oti normal springs 56. relay 53, vertical magnet 57 to battery. Upon the first vertical step of the shaft. springs 58 close and the vertical magnet circuit is completed by way of these springs, armature 59 of relay 53, which is operated. then through the said relay, vertical magnet 57 to battery. The vertical magnet 57 of connector switch H operates to step the shaft carrying the wipers 75, 76 and 77, opposite the level in which the desired branch exchange subscribers line is located. When the last digit of the number is sent a circuit is completed at each retraction of armature 60, from ground G to the rotary magnet 63 in multiple with relay 62, in a well known manner. The rotaryrmagnet 63 steps the wipers 7 5, 76 and 77 into engagement with the desired line. The energization of relay connects the test wiper 76 with the test relay 61. Now it the line is busy ground. will be present on the test cont-act engaged by the wiper 7c, whereupon a circuit will be completed for test relay 61 which willenergize; lock itself over a circuit from ground G armature 66, conductor 67, armature 65 and its make contact, break springs 68, break springs 69, thence through relay 61 to battery; and at springs connect the busy tone to the calling subscribers line.

Upon hearing this tone the calling subscriber will hang up, whereupon line relay 95 of the connector H will deenergize opening the circuit of slow acting release relay 52, which will deenergize, remove ground from condoctor 37, and complete the circuit to the release magnet 107. Ground being removed from conductor 37, relay 5 of selector E will deenergize and complete therelcasc magnet circuit of the selector. Thus all switches will be restored to normal.

If the line called, however, were idle no ground would be connected to the private wiper 7 6 and relay 61 would not energize. lelay 62 would deenergize an instant later and then a circuit may betrace'd from ground on conductor 67, armature 65 its break contact, lower winding of relay 6 1, armature 7 0 and its break contact, wiper 7 6, bank contact 78, conductor 81, relay 82 of the line switch C, and motor'magnet 83 to battery. Relay 82 operates only partially, that is, enough to open its armature break coir lacts but not to close any of its make con tacts due to a mechanical interlocking device controlled by the line relay 82. Relay 6st operates and locks itself at armature 85, and also closes the ringing circuit for the called subscribers telephone, which may be traced from generator M, break contact and armature H8 to springs 86. thence over the subscribers line, his condenser and ringer, springs 87, break spring and armature 89, upper winding of relay 54 to battery. R elay 54 so adjusted that it will not respond to alternating current. called subscriber A will continue intermittently until he ICIDOVQS his receiver from the switch hook, when relay 54. will energize, lock itself at armature 91, openthe ringing circuit at armatures S8 and 89, and connect the subscribers line to the back bridge relay at these arn'iatures and their make contacts. Relay 90 energizes and at armature 92 and its front contact completes the circnit of slow acting relay 93, which operates The ringing of the to reverse the polarity of the trunk conductors 36 and 38.. This reversal of polarity serves to operate a meter on the calling subscribers line or give supervisionto an operator, and also to'operate polarized relay 11, since current is now flowing in the same direction in both windings. Relay 11, on attractin'g its armature 50, connects ground G to the test wipers 33 and 3 1, bank contacts 45 and 16 and thence to multiple contacts 17; and 182 in the banks of interlinked tinder Gr.

Conversation may now take place between the two parties over the heavy conductors, battery being supplied to the calling party from relay 95 and to the called party from relay 90.

Upon the termination of the'conversation the release will take place as before dcseribed.

Suppose, however, that when the called party answers it is found that the calling. subscriber wished some other party in the branch exchange. Under these circumstances the calleo subscriber will dial the digit 1, relay 90 will retract its armaturein response thereto, and an impulse is sent from ground G9 armature 92 and its back contact, springs 96, relay 97 to battery. Relay 9? attracts its armature, cutting off line relay 951trom the trunk conductors 36 and 38 at springs 102 and 99, locks itself to ground on conductor 150, and prepares a dialing circuit at springs 101. The line relay 95 will not deenergize, however, as a local circuit has been completed for its upper winding from ground G and armature 102 and its make contact. Upon battery being cut oii" from the trunk conductors 36 and 38 relay 12 of the selector switch, will retract its armature, but relay 11 will remain energized, its local circuit being still completed. Now upon relay 12 retracting its armature a circuit is completed from ground G armature 50 and its make contact, armature and its break contact, relay 10 to battery; relay 10 attracts its armature, locks itself to ground at G", springs 28, armature 121 and its make contact. I Relay 12 in retracting its armature also connects ground G to conductor 143 and thence to relay 3 at ari'nature 1 1-2 and its break Contact. ,Relay 3 will attract its armature and maintain the polarity reversed over the trunk conductors '1 and 2 during the succeeding operations battery being supplied from the windings of relay ljto the calling subscriber.

At armature and its make contact ground is supplied over conductor 123 to the vertical magnet 1500f the finder switch G. The vertical magnet interrupts its own circuit and operates to step the shaft of the finder carrying wipers to 16% inclusive, until the vertical wiper 1.63 engages the contact 178, which has been grounded previous.- ly by the operation of polai'ized'relay whereupon a circuit is completed for the vertical test relay 151. Relay 151 operates to transfer the ground on conductor 123 to the rotary magnet and locks itself to ground G over a circuit through springslfie, conductor 152, armature 153 to battery.

As soonas the shaft of the inder'switclr stepped oil normal the springs 154, 155 and 156 were closed and a. circuit is completed from ground G springs155. conductor 157, relay 3 to battery. This circuit lS lli addition to the one hitherto traced and serves to maintain relay 3 energized during the subsequent operations. This relay isprovided so that the calling subscriber will only be charged with his original call during the: transferring operation. The rotary magnet 158 will operate to rotate the wipers -1642 inclusive breaking'its own circuit at each rotary step until the rotary test wiper 162 engages contact 182, which has also been grounded by the operation of polarized relay 11. thereupon a circuit will be completed for the rotary test relay 159fwhich on attracting its armature opens the rotary magnet circuit to stop the further rotation of the switch and locks itself to ground on conductor 152 through make springs 170. Relay 159 also completes a circuit from ground on conductor 152, spring 171. conductor 172, springs 127, off normal springs 26, release magnet 18 of selector E to battery. This release magnet will operate to restore the switch to normal, whereupon relays 5, 10, 11 and 12 will deenergize and the selector E will assume its original position with line relay 6 energized. Relay 10, upon deenergizing, completes a circuit at springs 144; from ground G springs 154, conductor 187. springs 144, conductor 188, relay to battery. Relay 185 energizes and locks itself to ground on conductor 152.

It will now be seen that the wipers 160 and 164 are connected to the multiples of the trunk line comprising conductors 36-4-38 and a circuit may now be traced for line relay 6 of selector E from battery through the upper winding of the said relay break springs 131. junction point 120, conductor 174. wiper 160. bank contact 181. conductor 36. springs 104. conductor 103. springs 10], which were closed by the operation of relay 9?. conductor 102, conductor 38. bank contact 180. wiper 164;. conductor 175. junction point 128. springs 130. lower winding of relay 6. to ground through the secondary of the induction coil. The primary of the induction coil is connected to a generator. Therefore a tone will be impressed on the trunk conductors 36 and 38 through the medium of the finder switch wipers. This will be audible to the called subscriber who will know that the apparatus is now in a condition tocstablish a connection. Upon the first digit of the dcsired"subscrihefs number being dialed by subscriber A, relay ()0 op'eratcsin response to the impulses and repeats them by means of springs 104 to the line relay (3 in the same'manner as a repeater. It will now be clear thatthe called subscriber A will only operate hiscalling device for the digits of the local subscribefis number, that is, the number he will call to connect with a second party in the local exchange will be the sanieas the local subscribers number except that of course tho" digit 1 is prefixed as has been hereinbelore described to initiate the operation of, the tinder switch. Upon the first digit of the subs'crib'efis number being called the back bridge relay 90 will retract its armature a plurality or times in response thereto and at springs 104 open the circuit of line relay 6, the selector stepping to the desired level in response to these repeated impulses and automatically rotating to find an idle trunk in the usual manner. By these operations the connection is extended to a connector switch similar to the connector H and a circuit is now completed for the line relay of this connector switch [through the springs of the back bridge. relay of connector ll in the same manner as i'n'the'case of the line relay of selector E. The line relay of the connector may now be controlled by the subscriber to control the'operation of this connector switch in complctinga connection to another subscribers line. The operation of this connector switch will be identical with the operation of the connector H which has been already described.

VVhilethe callingsubscribers line has been opened by the'operation of relay 3 it is still connectedinductively with that of the first called party through the condensers 134 and 145 over the heavy line conductors of the finder switch. Therefore,'should the line of the second called 'party be busy the busy. tone will be transmitted to both. the calling and original called parties in'multiple. This being the case, the called party may speak to the calling party and ask him if he desires to be connected with another subscriber. Suppose ing this to be the case the called party A. will replace his receiver on the switclihook whereupon the back bridge relay 90 will dcen'ergize opening at springs 104 the circuit for the line relay of the connector. which will I deenerg'ize. and the release of that connector and the selector E will take place in the usual manner. The connector H will not be released however as the conductor 37 has been grounded over a circuit which extends ;trolii G by means of wiper 161 of the finder. In the connector H is arelay.105 which is connected to the release trunk 37.. This relay is, therefore energized asllong as ground is present on the conductor 37 and keeps the circuit' of the release magnet 107 openat springs 106. The connector H will not be released then as long as the finder switch G remains cit normal. Should the calling party at any time during this interval replace his receiver onthe' switch-hook relay 4 will deenergize whereupona circuit will be completed from ground G break contact andarmature 135, arn'iature 136 and its make contact, springs 137 conductor 138; springs 156, release magnet 184, to battery, t is Will restore the finder to normal consequently removing ground from the release trunk conductor 37 whereupon the connector H will release.

However, if the calling subscriber holds the line, upon the called party A removing his receiver and dialing anothernuniber he willioperate the selector E and another connector in the same manner as previously described to establish a connectionwit-h a third party. If this party does not respond, ca llcd subscriber A can consult with the calling man to determine if anotherpartywill suflice; it so, the called party A may release andcall again in the samemanner as here-. tofore described. However, should the second called subscriber answer the back bridge relay of the connector will energize and close the circuit for the reversing relay in the same manner as described in the operation of connector H. Upon the polarity being reversed relay 11 in the selector E will ope-rate placing ground G on theconductor 139, springs186 which arenow closed, sp-ings' 1 56, release Inagnet184' of the finder switch to battery. This will release the finder G and the connector II will be released'upon'the original called subscriber A rcplacinghis receiver. Ground G is also placed on'the'vertical and rotary test wipers 33 and 34 respectively, to enable the finder G to find 'the multiple of the trunk line going to the connector which has been operated to connect with the third called party if it should be necessary to pass the call to a fourth party.

Upon the release of the finder G ground is removed from conductor 15? consequently relay 3 will deenergize and conversation may take place over the same circuit through the selector E as originally used;

All the apparatus used in the pissing of the call "is now normalJand the third called party may, in identically the same manner pass the callto a fourth party and so on, as long as desirable.

Upon the termination of the conversation the calling and called parties will replace their receivers on the switchhook, whereupon all the switches will* be restored to normal in the' usual manner, as has hitherto been described in the setting up of an ordinaryconneetion. Theoperation of the apparatus used when anoutgomg call is made ductors 138',

over the trunk conductors 1 and 2 will now be described; as previously stated thecon- 139, and l40-terminate-in a set of bank contacts in local branch exchange first selectors; upon a subscriber seizing these contacts by operating-one of these selectors ground is placed on the conductor 139, a circuit may now be traced from the said ground, break springs146, break-springs 147 lower winding of relay 4 to battery. Relay 4 will attract its armature, cutting-oil at springs 148 and 149 theselector E from the trunk line 1 and 2. Therefore this trunk can be used-in the usual manner for an out going call to themain exchange.

"Referring now to Fig. 4; this is a modification of the'systemabove described and is adapted to operate in a small exchange of not over 100 subscribers. Its operation is very similar to that hereinbefore described and will be readily understood with but a brief description. Upon the trunk line 201 and 202being seized. a circuit is completed for the line relay 203 of connector L which will energize and complete the circuit of slow acting relay 204. Relay 204 operates to prepare the vertical magnet circuit and to place ground on-the release trunk conductor 205 toprevent the trunk linel and 202 being seized for anoutgoing call. WVhen the next digit of the desired number is called the line relay 203 will operate in the usual mannerto complete a circuit for the verticalmagnet207 in series with slow acting relay 208. Upon the last digit being called the line relay completes the circuit of the rotary magnet 230 in multiple with relay 210'i'n the usual manner, to connect with the'line of the subscriber shown at B. If the called line is busy, the busy test relay 211 will be energized and the busytone will be transmitted to the calling subscriber. If the line is idle, relay 212 will operatev and the subscriber B- will be rung. Upon the removalof his receiver the ring cut ottrelay 218 will operate to extend the called. subscribers line to the back bridge relay 214-, which will attract its armature and operate the reversing relay 215 to reverse the polar ity of the trunk conductors 201and 202 and place ground on the vertical and rotary test wipers 224and231 respectively. This ground will extend from bank contacts 232 and 233 tothe vertical and'rotary test contacts inthe tinder switch? interlinked with the connec tor L. lVhen the conversation iscompleted both parties will replace their receivers on theswitchhook, after which, the release will take place in the well known manner.

So far theoperation of the connector L has been practically identical with that of connector H but ifthe subscriber 'B should transfer the call, the operation would be slightly difierent from that hitherto described; Assumingthis to 'be the case, the

p .by replacing his receiver on tracting its armature a dial for the digit party. B will operate his bridge relay will one, whereupon the back retract armature once and transmit an impulse from ground G to relay 217. Relay 217 attracts its armature and locks to ground G through oil normal springs 219. Relay 217 also places ground G'- on conductor 221 at springs 220 thereby completing a circuit to the vertical magnet 222 of the finder switch N. The vertical magnet of finder N operates in the same manner as that of finder G, interrupting its own circuit at springs 23% until the vertical wiper 223 engages the grounded vertical test contact 235, ground being placed on the multiple 232 by the vertical wiper of the connector switch L, whereupon relay 215 will energize, lock itself to ground on conductor 236 at. springs 237, and transfer the operating circuit to the rotary magnet 238 at springs 239.

The rotary magnet will continue to rotate the switch until the rotary test wiper 240 engages the grounded test contact 241, whereupon relay will energize, lock itself to ground on conductor 2230, and complete the release magnet circuit for the connector L at springs 242. .The circuit being traced from ground on conductor 236, springs 24:2, conductor 243, springs 2H, springs 2&5, release magnet 209 to battery. This will restore the connector switch to normal whereupon relays 214, 215, 217 213 and 212 will deenergize'. Upon relay 217 recircuit is completed from, ground G conductor 252, springs 251 conductor 258, relay 254 to battery. Relay attracts its armature, locks to ground on conductor 230, and prepares a circuit for the release magnet 228 of finder N.

' It must be here mentioned that upon the .first vertical step of the shaft of tinder switch N ground was placed on conductor 236 at oil normal springs 246 therefore relay 227 in the connector switch L will energize and serve to open the calling subscribcrs loop to the line relay 203 and keep the polarity of the trunk conductors 201 and 202 reversed, battery being supplied from the windings of relay 228.

As soon as the finder N connects with the multiples of the B subscribers line a tone .will be connected to the line from tone machine V over the energizing circuit of line relay 203 including the calling device of the subscriber B. By operating his dial the party B may control line relay 203 to cause the connector switch L to connect with an- ;other subscribers line in precisely the same manner as hereinbefore described. Should this line be busy, or not answer, the party B may converse with the calling subscriber, and if another connection is necessary, the .party B, may release the connector switch L the switch hook whereupon the connection will release in the usual manner. Upon the subscriber B rcmoving his receiver he will still be connected with the connector L because, ground G" was placed on the private conductor 249 to hold the line switch in the correct position, by wiper 2 18. The subscriber B may now call another number and operate the connector to connect with a third party. Prior to the answer of the second called party the calling party could by hanging up his receiver complete a circuit for the release-of the finder N and consequently the connector L also. Upon this subscriber answering he will energize the back bridge relay 21st, to complete the circuit of reversing relay 215, which 011 attracting its armature 250 places ground G on conductor 254, springs 255, springs 237, release magnet 228 to battery. Upon the finder N restoring to normal, ground would be removed from conductor 236, therefore, all the relays of the tinder would restore to normal and relay 227 of the connector would retract its armature and the calling and second called party would be able to converse over the same circuit through the connector as before used. All the apparatus used for the passing is now restored to normal and consequently the second called party may pass the call to a third subscriber and so on indelinitely.

The trunk line 201 and 202 may also be used for an outgoing call, being seized over the multiple 205, 206 and 207. Ground will be placed on the release trunk conductor205, thus completing winding of cutotf relay 228, which will energize and cut oti' the connector L front the trunk. This trunk may now be used to establish an outside connection.

a circuit for the upper It will, therefore, be seen that I have provided a simple and highly etiicient method of extending or transferring calls in a large or small automatic exchange and that this rc suit is attained in a novel and highly improved manner.

Having fully described and ascertained the features and operation of my invention what 1 consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

1. In a telephone system, a selector and connector switch, means for operating said switches in succession to connect with a called subscribers line, and means including a finder switch under the control of the called subscriber to reoperate said selector 'switcg while maintaining said connector operate 2. In a telephone system, a selector and said connector switch, means for operating said switches in succession to connect with 11. called subseribers line and means whereby the said called subscriber may release and reoperate said selector while maintaining said connector operated.

f scribers line, means under the control of the subscriber on the connected called line for reoperating the same elements of said selector switchto extend the connection to a sec ,ond called subscribers line, and means Iwhereby said first called party mayrelease said last extendedconnection.

5. In a telephone system, an automatic selector and connector switch, means for operating said'switches in succession to connect witlra called subscribers line, a relay in said connector controlled overthe called line and means controlled by said relay when thus controlled over said called line for again operating said selector to transfer the connection to a second called subscr befisline.

6. In a telephonesystem, a calling-subscribers line, connector switches, a selector switch controlled over said line to select one of said connector switches, meansiior operating said connector to connect with a called subscribers line,means under the control of the subscriber on the connected called line for releasing and reoperating said selector switch over a portion ofthe established connection to extend the call to a second called line.

7. In a telephone system, a trunk line, an automatic switch associated therewith, other automatic switches accessible to said switch, means for seizing said trunk line and for operating said first automatic switch to seize one of said second switches, and for operating the seized second switch to extend a connection to a called line, and connections whereby the same elements of said first automatic switch may be operated again over the connected called line to establish a connection with a second called line.

8. Ina telephone system, a trunk line. a pair o'hautomatic switches associated with said trunk line, ot-her automatic'switches accessible to said air of switches, means for seizing said trun line and for operating one of said pair of switches to seize one of said second switches, and for operating the seized second switch to extend a connection to a called line, and connections whereby the first one of said 'pair ofautomatic switches may be operated again from the CODIIQCtBdFCilllBtl line through the seized second switch and the other of said pair toestablis'h a connection to a second called line. v

9. In a telephone system, a trunkline, a pair of automatic switches associated with saidltrunk line, other automatic switches accessible to said pair of switches, means for seizing said. trunk line and for operating one of said pair 01 switches to seize one of said second switches, and for operating the seized second switch to extend a connection to a calledline, andconnections whereby the first one of said pair of automatic switchesmay be operatedagain from the connected called line through the seized second switch and thefirst otsaid pair to establish a connection to a second called line, and means for releasing-the second switch oi said pair responsive to the removal of the receiver on said second called line.

10. In a telephone system, selector switches, automatic switches individual thereto, connector switches accessible to said selector switches, means whereby a callingsubscriber may operate one of said selectors to extend a connection to a 'alled line through one of said connectorswitches, and means whereby the subscriber of the called line may operate the associated automatic switch to release said first used selector.

11. Ina telephone system, selectorswitches, automatic switches individual thereto, con nector switches accessible to said selector switches, means whereby a calling subscriber may operate one ofsaid selectors to extend a connection to a called line through one oi said connector switches, means whereby the subscriber on the called linemay operate the associated automatic switch to release said first used selector, and-means then operable whereby said called subscriber may op erate said first used selector switchto extend a connectionto a second calledline through a second one of said connector switches.

12. In a telephone system, automatic selector switches, connector switches accessible thereto, means controlled by a calling subscriber for seizing a selector switch and for then operating it to select one of said connector switches, and for operating said connector switch tofind a called line, together with means controlled from the called line over a part ofsaid extended connection for o jierating thesame elements of said first seized selector andanother connector to extend a connection to a second called sub.- scriber.

13.In a telephone system, a trunk line for handling incoming calls to a branch exchange. a selector switch in which said trunk line terminates, connectorswitches accessible to said selector, means for successively operating said selector and connectorto connect with a called subscribers line, means whereby the subscriber: on the connected called line can release the said selector while maintaining, connection with said calling line and means for reoperating' said selector to transfer the all to another line.

14. In a telephone system, a selector switch, trunk lines accessible thereto terminating in connector switches, means for operating said selector switch to connect with one ot said trunk lines and for then operating the selected connector switch to connect with :1 called subscribers line, means for closing a bridge across the selected trunk line, and means res 'iousire to the closure of said bridge for releasing said selector switch.

15. In a telephone system a selector and connector switch, means for operating said switches in succession to establish a talking connection with a called subscribers line. a finder switch, means controlled over the called line by a called subscriber for causing said finder switch to establish an alternatit e talking connection to said called subscribers line and release said selector switch.

16. In a telephone system a plurality of selector switches, connector switches. means for operating successively, a plurality of selector switches and a connector switch to connect; with a called subscribefs line, means whereby the subscriber on the said called line may reopcrate the same elements of one of said selector switches over a portion of the first extended connection to transfer the call to a second party.

.17. In a telephone system, selector and connector switches, means for operating a selector and connector switch to connect with a calledsubscribefis line, means whereby the said called subscriber may reopcrate said selector switch to extend a connection to a second called party, and means whereby the second called party can operate the same elements of said selector again to connect with another party while connection is still maintained with said calling: line.

18. In a telephone system, selector and connector switches, means for operating successively a plurality of selectors a nda connector switch to connect with a called sub- Stlllltl h line. means whereby the said called subscriber may reoperate the same elements of the selector switch used and another connector switch to extend the connection to a second called subscribefis line and means responsive to the removalof the second called partys receiver for releasing said first established connection.

19. In a telephone system, a selector switch. a tinder switch, connector switches accessible to said selector switch, means tor seizing said selector and operating it to select one of said connector switches, and for operating the selected connector switch to find a called line, a relay in said selector switch, a means whereby said relay is controllable over the extended connection by the subscriber on the called line for initiating the operation of said tinder switch.

20. In a telephone. system, a selector switch, a tinder switch, trunk lines accessible to said selector and tinder terminating in connector switches, means for seizing said selector switch and operating it to select one of said trunk lines, and for operating the seized connector switch to extend a connection to a called line. a relay in said selector switch, and means whereby said relay iscontrollable over the extended connection by the subscriber on the called line to initiate the. operation of said tinder switch to lind said selected trunk line.

21. In a telephone system, a selector switch, a tinder switch, trunk lines accessible to said selector and tinder terminating in connector switches, means for seizing said selector switch and operating it to select one. of said trunk lincs. and for operating the seized connector switch to extend a connec tion to a called line, a relay in said selector switch, means whereby said relay is controllable over the extended connection by the subscriber on the called line to initiate the operation of said tinder switch to tind said selected trunk line, and means operated upon said tinder finding said trunk line to release said selector.

In a telephone system. a selector switch, a tinder switch, trunk lines accessible to said selector and tinder terminatini'. in connector switches, means for seizing said selector switch and operating it to select one of said trunk lines, and for operating the seized connector switch to extend a connection to a called line, a relay in said selector switch, means whereby said relay is controll-able over the extended connection by the subscriber on the called line. to initiate the operation of said tinder switch to tind said selected trunk line, means operated upon said tinder finding said trunk line to release said selector and means then operable whereby the said called subscriber may again operate said selector to seize. a connector switch and for operating said connector switch to connect. with a second called subscribefs line.

In a telephone system, a selector switch, a tinder switch. trunk lines accessible to said selecto and tinder terminating in connector switches, means for seizing said selector switch and operating it to select one of said trunk lines, and for operation the seized connector switch to extend a corn nection to a called line, a relay in said selector switch, means whereby said relay is controllable over the extended connection by the subscriber on the called line to initiate the operation of said tinder switch to that said selected trunk line, and means operallltl subscribers lines controlled by the called subscriber over the established connection for opening said talking circuit atone point and for establishing a new talking circuit around said opening.

25. In a telephone system, subscribers lines, means for establishing a talking connection from a calling to a called one of said lines, means common to a plurality of subscribers lines controlled by the called subscriber over the ,es'tablished connection for opening said talking circuit atone point and for establishing a new talkingcircuit around said opening, and means controlled over said new talking circuit for extendin said talking circuit to include a second called subscribers line.

26.111 a telephone system, a trunk line, means for extendinga connection from said trunk line to a called subscribers line through a plurality of successively operated switches, and means controlled from the called line for extending the connection to a second called party by releasing and reoperating one of said switches used in said first established connection, while a connectionis still maintained between the calling and first called line and means for thereafter releasing said connection.

27. In a telephone system, a switch for connecting calling and called subscribers lines, a back bridge and a-front brid e for said switch, said back bridge inclu ing a relay, a finder switch, means under the control of said relayfor cutting ofi said front bridge, and means responsive to the disconnection of said front bridge for initiating the operation of-sa'id finderswitch.

28. In a telephone system, a calling subscribers line, aseries of automatic switches for connecting said line with a connector switch over a trunk line, and means for operating said connector switch to connectwith a called subscribers line, a front bridge across the conductors of said trunk line, and

means under the control of the called subscriber for disconnectingsaid front bridge fronisaid trunk line and maintainingsaid front bridge energized. e

29. In a telephone system, a calllng, subscribers line, a connector switch, aseries of automatic switches for connecting said line with said connector switch overa trunkline,

and means for operating said connector switch to connectwitha called subscriberso line, a front bridge across the oonductorsof said trunk line, means under the control of front. bridge,v

front bridge,

said

the called subscriber for disconnecting said andifor establishing,,a short circuit across said trunk iconductors and means underlthe control ofthe called subscriber, for opening and closing, said short circuit.

30.. In a telephone .system,..a calling subscribersline, a connector switch, a (series of automatic switches for connecting, 5 said 7 line with said connectorswitch over a trunk line, and means for operating said connector switch to connect, With a called ,subscribers line, a frontbridge across. the conductors of said trunk line, means. under the control of the called subscriber.foradisconnecting said and for establishingia short circuit across said {trunk conductors, and means under the control of the .calledcsubscriber iorv opening and closing saidtshort circuit to, send impulses back'over said trunk line, to reoperate one, ofsaid series of. automatic switches to transferthe callito a,.second called subscriber.

31. In a telephone system, a calling subscribers line, a series of automaticiswitches for connecting lsaidjline. with a connector switch over a trunk line and meansfor operating said connector switch toconnectwith a called subscribers line, a frontrbridge across the conductors of said trunk line, meansunder the controlfof, the ,calledsubscriber for disconnecting said front, bridge from said trunk line,t-;and means responsive to the cuttingofi' of said front-'bridge for releasing one of said series of switches 32. In a telephone system, main andiauxiliary switches permanentlyconnected inpairs, means whereby a calling subscriber can operate one of said main switches tomconnect with a called line and means whereby the subscriber on the called line can reoperate -main switch through :said auxiliary 1switch to transfer the call-to-a second-called me. a i

33: In a telephone system main andiauxiliar'y switches perinanently connected in pairs, means whereby a calling. subscribercanoperate one of'said main switchesto connect with, a called line, meanswwhereby the subscriber on the called line Y can reoperatesaid automatic. switches for connecting said Qline witlisaid connector switchover a trunk line, means for'operating said oonnectorg-swi-tch to connect,with a called subscribers:line, a front' bridge across the. conductors of saidtrunk line -means under: the controlof "the called subscriber for disconnecting said i front bridge from said trunk line, and means responsive to the cutting oft of said front "bridge for releasing one of said series of Switches and for placing said released switch under the control of said called subscriber.

35. In a telephone system, a trunk line, a pair of permanently connected automatic .switches, means for operating one of said switches over said trunk line to connect with it called telephone line, and connections between said switches whereby the said switch v subscribers whereby a calling subscriber may operate may be reoperated through said other switch over the connected called line to establish a connection with another called line.

, 36. In a telephone system, automatic switches permanently connected in pairs,

lines accessible thereto, means one of said switches toconnect with a called subscrihers line, and nnans whereby the subscriber on thecalled line can initiate the operation oi the other of said pair of switches to find his line.

37. In a telephone system, automatic switches permanently connected in pairs, subscribers lines accessible thereto, means whereby a calling subscriber may operate one of said switches to connect with a called subscribers line, means whereby the subscriber on the called line can initiate the operation of the other of said pair of switches to find his line, and means responsive to said switch finding said line for releasing said first switch placing it under the control of thesaicl called subscriber.

38. In a telephone system, automatic switches permanently connected in pairs, subscribers lines accessible thereto, means whereby a calling subscriber may operate one of said switches to connect with a called subscribcrs line, means whereby the subscriber on the called line can initiate the operation ot the other of said pairof switches to find his line, means responsive to said switch finding said line for releasmg said first switch and placing 1t under the control ot the said called subscriber,

and means whereby the said called subfirst switch and placing it under the control of the said called subscriber, means" whereby the said called subscriber may operate the first switch to establish a con' nection with another called line, and automatic means for releasing said other switch upon the response of the second called subscriber.

40. In a telephone system, automatic switches permanently connected in pairs, subscribers lines accessible thereto, means whereby a calling subscriber may operate one of said switches to connect with a called subscribers line, means wherein the subscriber on the called line can initiate the operation of the other of said pair of switches to find his line, means responsive to said switch finding said line for releasing said first switch and placing it under the control of the said called subscriber. means whereby the said called subscriber may operate the first switch to establish a connection with another called line, and means whereby said first 'alled party can release said last connection and call a third sub scriber. t

41.. In a telephone system, a selector switch, connector switches accessible thereto, means for operating said selector and a connector to establish a connection to a called subscril'iefs line, means under the control of the subscriber on the connected line for rcopcrating the same elements of said selector switch to extend the connection to a second called subscribers line, and means whereby said first called party may release said last extended connection.

42. In a telephone system, selector switches, connector switches, means for op erating a plurality of said selector switches and a connector switch to connect with :1 called subscribers line, a tinder switch, and meansimder the control of the subscriber on the connected called line for operating said finder switch to establish a new talking connection independent of the wipers of said selector switch.

43. In a telephone system. a selector and connector switch, means for controlling said switches in succession to connect with :1 called subscrib'ers line, a tinder switch, and means operated at will by a subscriber at the station on the called line for causine said finder switch to establish an alternative talking connection around said selector switch.

44. In a telephone system, telephone lines, automatic switches controlled from a calling one of said lines for extending a connection to a called one of said lines, means for supplying battery to said calling line, relay controlled means operative upon the response of the subscriber on the called line for reversing the direction of said battery supply, means controlled from said called line for then extending said connection to another'called one of said lines, and retainmg means for maintaining the direction of current flow renersed after "the receiver is replaced at thefirst: called station and before a response is obtained at the second called station. Q a

45. Ina telephone system, telephone lines,

automatic switches, means under the control 'of a party on acalling one of said hnesfor operating aseries oi said switches tin order to extend a connection to a first called one of said lines, means under controlof the party onthe said called line for reversing the direction of current projected back over the calling line,means controlled from the party on the said called line for directive'ly extending a connection to a sec mond called line from a point intermediate of .thecailling and the called lines, means for the party on the first called line discon- -necting while maintaining the connection from the calling line to the second cal'led :lineyandfor maintaining the said reversed direction of current, regardless of the responded or non-responded condition of the responding; and subsequently disconnecting.

a 46.111 aitelephone system, telephone lines, automat c switches, n eansunder the control of ia ipartylon a calhng one of said lines-for; operating aiseries of said switches in order to extend a connection to a first called one of said lines, means under control of the pa 'ty on the said called line for changing the character of current projected back over the callingline, means controlled from the party on the said called line for dlrectlvely extending a connection to a second ca'lled line from a point intermediate of the calling and the called lines, and means for the party on the first called line disconnecting while maintaining the connection from the calling line to the second called line and for maintaining the said changed character of current regardless of the responded or non-responded condition of the second called line.

47. In a telephone system, telephone lines, automatic switches, means under the control 7 of a party on a calling one of said lines for operating a series of said switches in order to extend a connection to a first called one of said lines, means under control of the party on the said called line for changing the character of current projected back over the calling line, means controlled from the party on the said called line for directively extending a connection to a second called line from a point intermediate of the calling and the called lines, means for the party on therfirst called line disconnecting while maintaining the connection from the call.- ing line to the second called line and for maintaining the said changed character of current regardless of the responded or nonresponded condition of the secondtcalled line and means for restoring the character of current projected back over the calling line to the initialcharacter consequent to the :partylon the second called lineresponding and subsequently disconnecting.

48. In a telephone system, lines, automatic switch mechamsm,means under control of a party on a calling one of said lines for op;

eratingsaid switch mechanism in order to extend a connection to a first called one of saidlines, meanscontrolled from the said called line for reversing the direction of current projected back over the calling line, means controlled by the party on the said called line for directively extending a connection to a second called line from a point intermediate of the calling and the called line, and means for the party on the firstcalled line disconnecting while maintaining the connection from the calling line tothe second called line for maintaining the said reversed direction of current regardless of the responded or non-responded condition of the sec'ondcalled line. s

19. In a telephone system, lines, automatic switch mechanism, means under control-of a party on a calling one of said lines for operating said switch mechanism in order to extend a connection to a first called one of said lines, means controlled from the said called line for reversing the direction of current projected back over the calling line,

means controlled by'the party .on the said called line for directively extending a connection to a second called line from a point intermediate oi the calling line and the called line, means for the party on the first called line disconnecting while maintaining the connection from the calling line to the second called line and for maintaining the said reversed direction of current regardless of the responded or non-responded condition of the second called line, and means controlled over the second called line for restor ing the direction of current.

50. In a telephone system, lines, automatic switch mechanism, means under control of a party on a calling one of said lines for operating said switch mechanism in order to extend a connection to a first called one of said lines, means controlled from the said called line for reversing the direction of current projected back over the calling line, means controlled by the party on the said called line for directively extending a connection to a second called line from a point intermediate of the calling line and the called line, means for the party on the first called line disconnecting While main taining the connection from the calling line to the second called line and for maintaining the said reversed direction of current is gardless of the responded or non-responded condition of the second called line, and automatic means effective in a predetermined time to restore the direction of current.

51. In a telephone system, a called trunk line, a calling subscribcrs line, a first connecting means operated over the calling line for connecting the calling line with the trunk line, a second connecting means for connecting the trunk line with the calling line, other means controlled over the trunk line responsive to a manual operation ensuing after said connection has been estal lished for eltectively operating the second means and for breaking down the connection established by the first means, and means controlled over the calling line for destroying the connection.

52. In a telephone system, :1 called two conductor trunk line, a :alling subscribers line, a first connecting means operated over the'calling line for connecting the calling line with the trunk line, a second connecting means for connecting the trunk line with the calling line, other means controlled over a conductor of the trunk line for effectively operating the second means and for breaking down the connection established by the first means, and means controlled over the I trunk line for destroying the connection.

53. In a telephone system, :1 called trunk line, a calling subscribers line, a first connecting means operated over the calling line for connecting the calling line with the trunk line, a second connecting means for connecting the trunk line with the calling line, other means controlled over a talking conductor of the trunk line for effectively operating the second means and for breaking down the connection established by the first means, and means controlled over the trunk line or alternatively over the calling line for destroying the connection.

54. In a telephone systen'i, a trunk line, a calling line, :1 called line, a first connecting means for connecting the calling line with the trunk line, a second connecting means for connecting the trunk line with the calling line, a third connecting means for connecting the trunk line with the called line to complete a connection from the calling line to the called line, and other means controlled over a talking conductor of the called line for effectively operating the second means and for breaking down the connection established by the first means.

In a telephone system, a trunk line, a calling line, a called line, a first connecting means for connecting the calling line with the trunk line, a second connecting means for connecting the trunk line with the calling line, a third connecting means for connecting the trunk line with the called line directively controlled from the calling line in order to complete a connection from the calling line to the called line, and other means automatically controlled from the called line consequent to a manual response thereon for effectively operating the second means and for breaking down the connection established by the first means.

Signed by me at Chicago, Cook County, Illinois, this 18th day of September, 1920.

JOHN E. GARDNER.

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