US1711744A - Telephone system - Google Patents

Description

May 7, 1929. J. E. osTLlNE TELEPHONE SYSTEM Filed May 8A, 1924 4 Sheets-Sheet l i May 7, 1929. J. E. OSTLINE V1,711,744

TELEPHONE SYSTEM Filed May 8, 1924 4 Sheets-Sheet 2 I May 7, 1929. E, CS1-LME 1,711,744

TELEPHONE SYSTEM 4 Sheets-Sheet '5A Filed My 8, 1924 Jahn E. /ZHE May 7, 1929- l.1. E. osTLlNa l1,711,744

TELEPHONE SYSTEM Filed'May 8 1924 4 Shets-Sheet 4' FNM OTHER' MARKERS:

Inu-51171? Jahn E. slme Patented May 7, 1929.

UNITED" STATES? PATENT oFFicE.

JOHN E. OSTLINE, OF LVERPOOL, ENGLAND, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO AUTOMATIC ELECTRIC TNC., 0F CIillCGOJ ILLINOIS', A CORPORATION OF DELA- y WARE.

Application inea May s,

This invention relates to telephone systems in general, but more particularly to telephone systems using manual switehboards and in which automatic switches are employed for extending or distributing calls to the operators. Generally stated, the object of the invention is to'provide an improved and highly' efficient call or traffic distributing system.

Special objects of the invention are the provision in a system of this character of new and improved circuit arrangements whereby vthe calling party after hanging up always secures a connection to an idle operator for the next call regardless of whether the previous connection tothe called line has been taken down or not whereby the called party can originate a call to an idle operator immediately after he vand the calling party have hung up and before the previous connection is taken down; whereby the sleeves of bothA the calling and called partys multiple jacks will test non-busy to calls for these lines immediately after the calling and called parties have hung up and before the connection has been atoi instantly receives a guard tone upon failure to properly depress the ringing master key at the time of inserting the plug in the multiple jack of lthe called line; whereby the operator can cleai a pern'ianent, that is, grounded or short circuited line, .out of her position b v momentarily operating a key, which will at the same time signal the switchboard attendant andplace a trouble tone on the multiple jack sleeve of the defective line; and whereby separate peg counts are obtained automatically of calls completed in the multiple and those not completed. A l ln a system characterized by the invention, a subscriber whose line is arranged for single or four party jack per line service and which terminates in an individual line switch and multiple jack, makes a call in the following manner: He takesA down his receiver and the individual line switch automatically seizes for him a preselected trunk leading to an operators open position. Common position equipment will niark and store the call and light a pilot lamp on the operators key shelfk to indicate the number of calls stored. The subscriber upon being connected with" the trunk receives a. tone indicating` this fact.'

The common position marking and storingV equipment automatically connects thel trunk taken down; whereby the oper- TELEPHONE SYSTEM.

1924. Serial No. 711,782.

to the operators telephone circuit in the saine order as the call was originated in relation to other calls. This will light a common call lamp on the operators key shelf to indicate that a trunk is connected to her set. In case of a .restricted line making a call7 a restricted service lamp will also light, thereby giving the operator positiveindication as to the kind of service to be allowed. The tone given to the subscriber also stops, thereby giving limi positive indication that the operator is ready to take his number. After the desired number has been obtained by the operator, she selects any cord circuit on her position and tests the line wanted for the busy or out-A l of-order tone. If the line called is not busy or out of order, the operator inserts the plug in the inult-iple jack of this line and depresses momentarily the common frequency key corresponding to the party desired on theline. This starts the automatic ringing of the wanted party7s bell, causes a finder switch to connect the cord with the trunk in use, and causes the neXt call to be automatically connected to the operators set. If the line called is busy the operator momentarily depresses the common busy key, without inserting the plug in any jack, and this will place a busy tone on the calling partys line until he hangs up, and the next call is automatically connected to the operators set. If the part-y called is on the same line as the calling party the operator will get a revertive tone when testing for busy, whereupon she will connect the party through to a special operator who will complete the call, and the next call will be automatically connected to vthe operators set. If a trunk to an ide operator seized by a line owing to a short, ground, or any other class of permanent. itis evident that some means must be provided so that the operator can get awayl from this line to permit the neXt call to come in. Thisis done by momentarily depressing the common permanent key which will place an out-of-order tone on the multiple jack sleeve of the permanent7 line and lautomatically connect the next call te the Operators set. The depressing of the common permanent key wili 4also automatically give a signal to the switchboard man that a permanent exists and will prevent wrong busy reports on succeeding calls for this line. When the calling party hangs up on an established connection the operator receives standard lamp supervision and both the calling and called partys lines become non-busy .in the multiple immediately upon their receivers being restored and before the connection is taken down. Both parties can immediately originate new calls, which eliminates the need for any recall features.,

The invention is illustrated in the accompanying drawings, in which Fig. 1 is a circuit diagram of two manual substations A and A0 on the same line, the latter showing the bell and condenser only, a Keith or plunger` type line switch C, and a trunk relay group R3 Fig. 2 is a circuit diagram of a trunk finder F, a cord circuit E, a Keith or plunger type line switch C', and party line manual substations A', A2, A3, and A4;

Fig. 3 is a circuit diagram of a master switch M, a marker distributor S2, a marker S', and a set-up control switch S5;

While Fig. 4 is a circuit diagram of an operators head telephone set and busy test equipment O, together with the necessary keyshelf and metering equipment.

Proceeding now to the detailed explanation of the circuit drawings and referring first to Fig. 1, the manual telephone substations A and A0 are connected in bridge of a pair of talking conductors and are arranged for party line ringing currents of different frequencies. As represented herein, substation A comprises essentially the receiver 2, switchhook 3, transmitter 4, condenser 5, and bell 6. The line conductors 11 and 12 of the sub-- stations A and Ao terminate at the central office in the individual line switch C and multiple j ack J. The line switch C is of the well known Keith or plunger type, modified, however, in circuit arrangement, to be hereinafter explainedA in detail in connection with its operation. It has access to a plurality of ltrunk lines extending to trunk relay groups, one of which is shown at R. The trunk relay group R consists essentially of a plurality of relays, together with associated common alarm and tone equipment, and individual signal equipment; also suitable circuits for performing the necessary functions, as will be pointed out hereinafter.

Referring to Fig. 2, the trunk finder F may be briefly described as a rotary line switch whose movable terminals or wipers have no normal position, and which have movement in a forward direction only. In further explanation, it may be stated that the wipers of this switch advance upon the energization of the stepping magnet, rather than upon its deenergization. As shown in the figure, each trunk finder F is associated with a cord circuit, such as E, and has access to a plurality of trunks, each of which extends to a trunk relay group, such as R. The cord circuit E consists essentially` of a plurality of relays, a

supervisory lamp L', a plug P', together with associated common ringing generators G', G2, G3 and G4, to deliver the desired current frequency, and suitable circuits for performing the necessary functions, as will be pointed out hereinafter. The line switch C is similar to C, in Fig. 1, while the substations A', A2, A3, and A42 (the latter three having their bell and condenser only shown in bridge of the line) are similar to substation A, Fig. 1, and also have their bells adjusted to respond to different frequency ringing currents.

In Fig. 3 will be found the master switch M which is associated with a group of line switches, such as C, and trunk relay groups, such as R, in Fig. 1, andwhich functions to step the line switch plungers before an idle trunk immediately after any line switch plunges in on the trunk previously selected. The marker distributor S2 advances thewipers 25() and 251 over the banks B3 and B4, respectively. The set-up control switch S3 advances the wiper 260 over the bankV B5. These switches are all similar to the trunk finder F, Fig'. 2. There is one marker distributor, such as the switch S2, provided for each position. The wiper 251 of switch S2 is connected to a starting common which is'multipled through each trunk relay group in the position. Upon each contact in the bank B2 is terminated a start conductor which leads to a marker, such as the switch S. In practice, a number of markers would be provided equal to the maximum number of simultaneous incompleted calls likely to occur in the position.

tach marker is associated with a test Contact in bank B2, which serves to advancey the marker distributor S2 when the marker in question is seized. A test conductor from each trunk relay group in the position terminates in the bank B'. An operating conductor from each trunk relay group terminates upon a contact in the bank B2. The relay 262 of the set-up control switch S3 is connected to a starting common which is multipled through each marker in the position. A test conductor from each marker is terminated upon a Contactin the bank B5.

l shows an operators anti-sidev tone head telephone set and busy test equipment O, together with the necessary keyshelf and metering equipment, which consists essentially of a plurality of relays, revertive tone equipment, induction coils I and I', jack J2, plug P2, no toll and cal lamps L2 and L2, respectively, pilot lamp L4, etc., busy key K, permanent key I ring start7 keys K2, K2, K4 and K5, permanent and'busy peg count meter N, completed call peg count meter l and suitable circuits for performing the necessary functions, as will be pointed out hereinafter'.

Having briefly explained the purpose of the invention and the apparatus'involved in car-V rying it out, the operation ofthe equipment may now be explained more in detail. For this purpose it will be assumed that the subscriber at substation A, Fig. 1, desires'to yobtain connection with the subscriber at vsubstation A, Fig. 2. c In order to do this, the subscriber atsubstation A removes yhis receiver andwhen he is cut in to the operator he gives her the number of the desired subscriber.

Vhen the receiver' is -removed from the switchhook at substation A, line relay 13 of plunger line switch C energizes over a circuit traced 'from'ground at the guard tone equipment, spring 15 and its resting contact, line conductor 12, switchhook 3 and its working contact, receiver 2, transmitter 4, line conductor 11, spring 14 and its resting contact, and relay 13 to grounded battery. Relay 13, upon energizing, closes a circuit for pull-,down coil 19 traceable from ground at the guard tone equipment, armature r2O and its working contact, pull-down coil 19, conductor 211, and armature 217 and its rest-v ing contact, Fig. 3, to groundedbattery. Pull down coil 19, upon energizing, operates both the plunger arm 17 and the cut-ofi' armature 16; the former, through the medium of its plunger (not shown) forces the bank springs 23-26, inclusive, into engagement respec' tively, with the contacts 27-30, inclusive, and the latter disconnects the line conductors 11 and 12 from theV line relay 13 and from ground, respectively. By the engagement of bank springs 23-26,vinclusive, with contacts 273(), inclusive, the line, restricted service, and holding conductors are extended to the trunk relay group R.

By the extension o't the line conductors, at bank springs 23 and 26, and contacts 27 and 30, a circuit'is closed from ground, lower winding of relay 40, contact 30, spring 26,

line conductor 11, transmitter 4, receiver 2, Y working contact otswitchhook 3 and sald.

switchhook, line conductor 12, spring 23', contact 27, and upper winding 'oit relay 40 to grounded` battery. Relay 40, upon energizing, places aftrunk tone on'the calling subscribers line circuit at armature 46, which will persist untill his call is cut in to the op erator as will be more fully explained hereinatter. This trunk tone circuit may be traced from the trunk tone apparatus indicated, armature 76 and its resting contact,

armature 68 and its resting contact, resting contact ot armature 52 and said armature,

and working Contact of armature 46 and said armature to the subscriber-s line circuit. Relay also closes 'a circuit for the hold-in coil 18 of the line switch C, traceable from ground, hold-in Acoil 18, spring 24, contact 28, a-nd armature 47: and its working contact to grounded battery.` Hold-iny coil 18, upon energizing, holds the cut-otf armature 16 and plunger arm 17 in operated positionafter the kpull-down coil 19 has deenergized'through the falling back of armature 2O when relay 13 deenergizea-the latterrelay being slow acting lto make this a positive operation. In multiple with the above traced circuit, a circuit is also completed over the conductor 210 extending to the master switch bank contact upon which the master switch wiper 219 is now resting for energizing the starting relay 215 of the master switch M. Upon energizing,relay 215 closes a circuit for the locking magnet 213, which unlocks the master switch shaft andthus brings about the realignment o't all the idle line switch plungers in front ot the nextidle trunk line. The locking relay 213 also closes a circuit for the open main relay 214, which, upon energizing, -disconnects theV common conductor 211, at armature 217, from grounded bat-V tery in order to prevent' any of the line switches from being operated before the master switch comes to rest. rIhe master switch wiper 219 rotates over the bank contacts B in Y It will-be observed that as soon as the line.

relay 40 of the trunk relay group R energizes and the circuit is completed for the holding winding 18, battery potential will be placed on the sleeve Vof conductor, which extends to multiple connected jacks in the positions of the switchboard which have access to the line of station A. This renders the calling line busy to other calling lines as will be .explained hereinafter. I

. A further result of the energization of line relay 4() is the removal of ground, by way of armature 50 and conductor 230, from the contacts associated with the trunk relay group R in the multiple test banks of the markers; and the grounding of the common start conductor 253 leading 'to the llO marker distributor S2, Fig. 3. For the sake of explanation we may assume that the marker distributor hasl preselected the marker S` as the next marker to be used;

therefore, when relay 40 becomes .energized a circuit is closed from ground, armature 62 and its resting Contact, armature 57 and its resting contact, armature 51 and its working contact,kstart conductor 253, wiper 251 of the marked distributor Srstcontact in bank B4, resting contact of armature 239 and said armature, and line relay236 to grounded battery. Line relay 236, .upon

energizing, closes a circuit for switching.

ner to seek an ungrounded contact in the test bank B. llVhen the ungrounded test Contact associated with the trunk relay group R is reached the switching relay 235 will energize and open the circuit of relay 236 at armature 239.

As relay 236 is slow'to decnergizc a circuit will momentarily be closed lroin ground, working contact or' armature 244 and said armature, working contact of armature 233 and said armature, wiper 232 and the contact upon which it is now standing, marker 'release trunk conductor 230, armature 50 and its working contact, armature 67 and its resting contact, resting Contact controlled by armature 56, armature 49 and its working contact, and relay 42 to grounded battery. Relay 42, upon energizing, closes a locking circuit tor itself by placing ground upon marker release trunk conductor 230 by way ot armature 62 and its working contact, resting contact controlled by armature 56, resting contact ot armature 67 and saidvarmature and working Contact of armature and said armature. This ground will maintain switching relay 235 o't marker S energized `after relay 236 has deenergized, and will also uiake the trunk relay group lt busy in the multiple test banks of' the markers.

`further result ot' the energization of relay 42 is the removal of ground from the starting conductor 253 at armature 62.

- A further result ot the energization ot switching relay 235 is the placing oitl ground by way of armature 237 upon the contact associated with the marker S in bank B3 of the marker distributor S2, whereupon the motor magnet 252 of marker distributor S2 will operate to advance the marker distributor S2 into engagement with the next marker. A still further result oit the energization of relay 235 is the closure of a cir# cuit from ground, working Contact ot armature 241 and said armature, conductor 245, through the lamp L4, Fig. 4, to battery. Thus it Vwill be seen that a lamp is lighted whenever a marker is taken for use, in order 4 that the operator and supeiwisormay know Tit how many calls are ahead in waiting.

A still further result of the energization of switching relay 235 is the removal oit ground, by way of armature 240, from the contact associated with the marker S in the bank B5 of the set-up control switch S2. A still further result ot the energization of relay 235 is the closure ot' a circuit from ground,

working contact ot armature 242` and said armature, common start conductor 246, through relay 262 of the set-up control switch S3 to grounded battery. For the purpose of explanation we may assume that the set-up control switch S2' is at 'thistirne 1n connection with some marker other than the marker S. Theswitching relay 264 and start relay 262 are therefore in energized position, and the placing of additional Vground on start conductor 246 of relay 262 is without eliect upon line relay 263 because of the open circuit at armature 270. When the marker with which the switch S3 is in engagement completes its operation the switching'relay 264 will deenergize,whereupon a circuit is closed from ground, working contact of armature 266 and said armature, resting contact oi armature 270 and said armature, through line relay 263 to grounded battery. Relay 263, upon energizing, will close a'circuit for the switching relay 264 and the stepping magnet 261 in series at armature 267, and at armature 268 connects t-he wiper 260 .toV the junction oit switching relay 264 and stepping magnet 261. The set-up control switchS3 will now operate in the usual manner to seek an ungrounded Contactin the bank B5. `When the ungrounded contact associated with'the marker S is reached the switching relay 264 will energize and open the circuit of line relay 263 at armature 270. Y

As relay 263 is slow to deenergize a circuit will momentarily beclosed lromground, working contact of armature 267 and said armature, working contact of armature 269 and said armature, armature 265 and its working contact, wiper 260 and the contact with which it is nowl engaged, armature 240 and its working Contact, wiper 233 and the contact with which it is now engaged, con.-

ductor 231, resting contact of armature 70 v talking conductors of the calling line to ythe operators anti-side tone head telephone set @,Figz 4, at armatures 73 and 80, by way of conductors 300 and 306. respectively, it being Vassumed for the sake of explanation that thel position is occupied and that the plug P2 is ltltl therefore inserted in the iack J2. vl/llith the plug P2 inserted in the jack J 2 it will be observed that a local battery talking` circuit is completed which includes ground at the j ack J2, the transmitter, right hand windings of the induction coil l, and relay 308. Relay 303, being energized has disconnected battery from armatures 311, 342 and 313, whose function-will be explained hereinafter. A further result oli the energization of relay 45 is the closing of a circuit for white common call lamp L2, at armature 76, by way of conductor 304. This white serves to notify the operator that a trunk is connected to her set. Still a further result of the energization of relay 45 is the disconnection of the trunk tone fromv the calling subscribers line, at armature 76, whereby the subscriber knows that his call has been extended to an operator and t-hat she is ready to take his orderV without waiting for the usual Number please.

The operator having obtained the desired number, mayl complete the connection to the multiple jack J associated with substation A by the use of any .cord circuit, not in use, in her position. For t-he purpose of explanation we will assume that the operator uses the cordV circuit E, Fig. 2, and that she tests the called linein the usual manner by touching the tip of the associated plug to the sleeve of the desired multiple jack. If the called line is found not busy and tree from` the trouble tone she then inserts the plug P into the multiple jack J and depresses momentarily the common frequency selecting key corresponding to the party desired on the line, l

in this ease 33 cycle key K4, Fig. 4.

Upondepressing the key K4 a circuit is closed which may be ytraced from ground, holding winding 188 of the lline switch C, Fig. 2, sleeve conductors oit jack J and plug P, resting contact of armature 144 and said armature, upper winding of relay 136, resting contact controlled by armature 163, conductor 341, working contact of spring 329 and said spring, conductor 344, and magnet 345 to grounded battery. Magnet 345, -upon energizing, operates the pegV count meter N and registers the completed call in the usual well known manner. Holding winding 188, upon energizing, operates the bridge cut-0H armature 186 to disconnect the line relay 183 from the line at springs 184 and 185, but has not suiicient power to operate the pull down armature. Relay 136, upon energizing, closes a locking circuit for itself at armature 163, from ground at holding winding 188, as previously traced, and cuts magnet 345, Fig. 4, out of circuit. A further resultotY the energization of relay 136 is the closing of a circuit tor relay 109 of vfinder switch F atei-mature 162 traceable from ground, working contact of armature 162 and said arma# ture, armature140 and .its resting contact, resting Contact of armature 112 and said armature, and relay 109 to grounded battery. Relay 109 energizes but its function will be explained hereinafter.` A still further result of the energizationl of relay 136 isthe closing of a circuit for relay 135 at armature 164 traceable from ground, working contact ot armature 164 and said armature, lower winding ot' relay 135, resting contact ot armature 157 and said armature, conductor 341, working contact of spring 329 and said spring, conductor 344, Vand magnet 345 to `grounded battery. Relay 135 energizes only partially over this circuit, it being a. so v.called two step relay, and armature 158, also marked 1, is the only one attracted at this time. When armature 158 is attracted, however, it closes a locking circuit for relay 135 traceable from ground, working contact of armature 164 and said armature, relay 135, working contact ol armature 158 and said armature, and working contact of armature 163 and said armature to grounded battery. Relay 135 Returning to a further consideration of the` operation ot' relay 109 ofthe trunk iinder switchV F, it may be seen that a circuit is closed ormagnet 107 at armature 117 by Vway of normally grounded bank contact, wiper 105, and armature 114 and its resting contact. Magnet 107 energizes and deenergizes over this and similar circuits, involving the grounded holding bank contactsl of unseized trunk relay groups, thus operating to rotate the wipers 104-106, inclusive, until they find the bank contacts to which are'connected the line conductors 101 and 103 and the holding conductor 102, nowv havingbattery potential thereon, ot the seized trunk relay group R.

When the wipers reach the contacts, magnet 107 is prevented from operating further, while switching relay 108, heretofore short circuited, will energize and open the circuit of relay 109 at armature 112. As relay 109 is'slow to deenergize a circuit will momentarily be closed from ground, working contact of armature 116 and said armature, working contact of armature 113 and said armature, resting Contact of armature 137 and said armature, ,and lower winding otrelay 130 to grounded battery.v Relay 130energizes only partially over this circuit, it being a so called two step relayan`d its functions will be explained hereinafter.

A further result of the slow releasing of relay 109 is the momentary closing of a circuit fromground, working contact of armature 116 and said armature, working contact of armature 114 and said armature, wiper 105, holding conductor 102, working contact vof armature 63 and said armature, and relay 44k to grounded battery. Relay 44, upon'energizing, closes a locking circuit for itself at armature 71 by way ot armature 48 and its working contact, and opens the circuit of reeoy lay 43 at armature 70. Relay 43,`upon deenergizing, opens the circuit of relay 45 at armature 65. Relay 45, upon deenergizing,

Yle

disconnects the operators head telephone set O, Fig. 4, at armatures 73 and 80; and disconnects the white call lamp L3, Fig. 4, at armature 78. The extinguishing of the lamp L3 indicates to the operator that there are no calls in waiting, while the disconnecting of the operators head telephone set makes it available Jfor the next incoming call.

A further result ol' the deenergization el relay 43 is the opening of the circuit of the switching relay 264 ot the set-up control switch S3, Fig. 3, at armature 64. Relay 264, upon deenergizing, closes a circuit i'or relay'263 at armature 270 by way of armature 266 and its working contact. At the same time the circuit ot the switching relay 264 is opened at armature 64 the circuit ot the switching relay 235 et marker S is temporarily opened at armature 67, when this armature restores to its normal position, the armature 72 of' relay 44 being in its operated or open position at this time. Relay 235, upon deenergizing, opens the circuit of the pilot lamp L, Fig. 4, at armature 241; opens the circuit ol' relay 262 at armature 242; and places ground on the contact in bank 12,5 upon which wiper 260 is standing, at armature 240. Relay 262 deenergizes and opens the circuit of magnet 261 at arn'iature 265 betere relay 263 energizes and closes a circuit for this magnet at armature 268. From this` it will be seen that the set-up control switch S3 becomes dissociated 'from the marker i and available for future us Returning toa further consideration ot the partial operation of relay 130 oit the cord circuit E, it may be seen that a locking circuit is closed for the relay at armature 140 traceable :l'rom ground, working Contact of armature Y162 and said armature, armature 140 and its working Contact, and relay 130vto 'grounded battery. Relay 130 does not, however, fully energize at this time due to its top winding being shunted out by a multiple circuit which may be traced lfrom ground, working contact et armature 48 and said armature, 1, working contact of armature 71 and said armature, working` Contact of armature 69 and said armature, conductor i, 102, wiper 105, armature 114 and its workin g Contact, working contact of armature 113 and said armature, resting contact of armature 137'and said armature, and lower winding et relay 130 to grounded battery.V A further result oit the partial energization of relay 130 is the preparation ot a circuit for supervisory lamp L at armature 138. Still a 'further result of the partial energization of relay 130 .is the closingl oi the ringing circuit at armatures 141 and 145 which may be traced from ground, working Contact ol armature 141 an d said armature, armature 154 and its resting contact, working contact ot armature 161 and said armature, tip conductor of plug P and jack T, line conductor 181, condenser and if/iifmfl thirty-three cycle bell at substation A', line Y When the called subscriber at station A i answers by lifting his receiver from the switch-hook the bell and condenser, which are in bridge the line, are replaced by the transmitter and receiver in bridge of the line. This permits relay 134 to energize and upon doing so it'opens the ringing circuit at armatures 154 and 155, closes the talking conductor through at the latter, and closes a locking circuit for itself at the former which may be traced from ground, working contact of armature 141 and said armature, armature 154 ane its working contact, and upper winding ci relay 134 to grounded battery. As a further result' of the energization of relay 134 a circuit is closedtor relay 131 at armature traceable from ground, armature 139 and its restiiig Contact, upper winding of relay 131, werking contact oi armature 161 an-d said armature, tip conductors-of plug P and jack il", line conductor 131, receiver and transmitter at substation A', line conductor 182, ring conductors of jack J and plug P, armature 155 and its working contact, resting contact oit' armature 143 and said armature, and lower winding of relay 131 to groundedvbat tery. Relay 131, upon energizing, closes af locking circuit for itself at armatures 146 and 14'?, and closes a holding circuit tor'the upper winding of relay 136 in series with the hold-in winding 188 of line switch C, at armature 148. Conversation may now take place as desired. TWhen the calling subscriber restores his receiver to the switchhook the circuit oi line relay 40, Fig. 1, will be opened, whereupon the said relay will deenergize and remove battery from the release trunk conductor at armature 47 and-the release of the line switch will take place in the usual manner. A further result of the deenergization of relay 40 is the opening of the circuit of relay'44, and the opening of the shunt circuit of the top Winding of relay 130, Fig. 2, which also acts as a holding circuit for switching relay 108, at armature 48. Relay 108 deenergizes to restore the finder F to normal, while relay 130 now fully energizes to ground at armature 162, oyer a circuit previously traced, and actuates its armatures marked 2 whose functions will be explained hereinafter. Relay 44, upon deenergizing, prepares'a circuit for the trunk tone at armature 68, places ground n conductor 102 at armaturev 69, byway of armature 64 and its resting contact, and prepares a circuit for relay 43 atarmature 70. A further result of the deenergization of relay 40 is the preparation of the marker release trunk conductor 230 for its normally grounded condition at armature 50. Afstill further result of the deenergization of relay 40 is the opening of the circuit of relay 42 at armature 49. Relay 42, upon deenergizing places ground on the marker releaseA trunk conductor 230 and prepares ground for the start Conductor 253 at armature 62, and prepares several other circuits for future use which need not be specifically pointed out at i this time. rihe trunk relay equipment R is now at normal and may be used to extend other connections.

Returning to a further consideration ofthe complete operation of relay of the cord circuit E, Fig. 2, it may be Seen that a circuit is Vclosed for supervisory lamp L at armature 139 traceable from ground,armature 139 and its workingr contact, working Contact of armature 156 and sai-d armature, and supervisory lamp L to grounded battery. The lamp L, upon lighting, notifies the operator of the termination of the conversation. From this it will be observed that the restoration of the receiver atthe calling substation causes disconnect supervision to be given the operator Whetherl the receiver at the called substation has been restored or not. In case the calling subscriber abandons the call and hangs up before the called party answers the two-step relay 130 will fully energize rand actuate its armatures marked 2 as alreadyV described. Armature 142, upon being actuated -in such case, closes an energizing circuit for ringing relay 134 whereupon this relay' energizes to disconnect ringing current vfrom the called y partys line. At the same time the supervisory lamp L is lighted to notify the operator of the abandonment of the call and permit her to take down the connection.

When the calledsubscriber restores his receiver the batteryv feed relay 131 deenergizes in the usual manner, whereupon the shunt around the lower winding of relay 136 is opened at armature 148 and the two windings of this relay are now connected in series vwith the hold-in winding 188`of line switch C. The added resistance in relay 136 causes the hold-in winding 188 to release theel-mature 186` whereupon the springs 184 and 185 are returned to normal. and the line switch C is ready for future use. It will be observed that this is accomplished without the operator taking down the connection. A. further result of the added resistance in relay 136 isto prevent the testrelay 307, Fig. 4, from energizing when testing the multiple jacks of this line with the tip of another cord circuit.

rlhe operator may now take down the connection by pulling the plug` P from the ack J, whereupon thefrelay 136 deenergizes and causes the simultaneous deenergization of; relays and 130. Relay 130, upon deenergizing, causes relay 134 to also deenergize, whereby the cord circuit E is returnedto normal and available for futurev use'. n

An explanation will now be given of the operation should the called line be busy. It will-be assumed that the called substation A is in use when the operator tests the sleeve of the associated multiple jack with thetip ofthe plug-belonging to the cord circuit E. At this time. a circuit may be traced from groundre lay 307, conductor 340, resting contact of armature 161 and said armature, tip of plug P, sleeve of multiple jack J, sleeve of multiple jack at another switchboard section',r through the relay ofv the cord circuit which is associate d withthe last mentioned multiple jack to battery, or to battery Vat contacts of a relay similar to 40 if the line is busy due to an outgoing call. Relay 307, upon energizing, will close a circuit through the left-hand Winding of the operators induction coil I at armature 310. The current flowing in this circuit will induce a click in the operators receiver, thus advising her that the called line is busy. The operator will then momentarily depress key K, which Causes the busy tone to be placed upon thetruuk relay group which at this time associated with the calling line set up on the storing equipment; causes the next call to be connected to the operators set, and causes the permanent and busy call7 meter' Nte operate to register the call.

lVhen the key K is depressed a circuit may be traced from ground, spring 320 and its working contact, conductor 302, working contact of armature 75 and said armature, upper winding of relay 41 to grounded battery. Relay 41, upon energizing, closes a locking circuitv for itself at f armature V55 byV way ground at-armature 48; closes the circuit of the busy' tone at armature 52 by Way of armature 58; and transfers the holding` circuit of relay 43 from ground at armature 64 tok :ground at key K, Fig. 4. The busy tone vpersists until the calling subscriber restores his receiver. Av further result-of the depressing of the key K is the closing of a circuit for relay 346 at spring 321, whereupon relay 346 becomes energized` to operate the meter N and register the busy call.-

VJhen the operator releases the key l the circuits of relays 346 and 43 are opened at springs 321 and 320, respectively, Whercu pon they deenergize. Relay 43, upon deenergizin opens the circuit of relay 45 at armature 65, whereupon relay 45 deenergizes to disconnect the operators head telephone set O from the relay trunk group R and extinguish the call lamp L3, thus notifying her of the dis-v connection and rendering her set available for future. use. A further-result of the deenf ergization of relay 43 is the removal of ground fromv Conductor 231 and the restoration of ground to the conductor 102 at armature 64. The removal of ground from conduetor 231v and the temporary removal ot ground from conductor 230 at armature 67 causes the call assigner S3 and marker S to restore to normal and become available for further use, as has already been explained. When the calling subscriber restores his receiver, upon hearing the busy tone, the line relay i0 deenergizes, whereupon battery is removed from the release trunk conductor, the line switch is released, and the circuit of relay lf2 is opened so as to become deenergized and perform its functions, all of which have been already explained. A further result oit' the deenergization oit relay l0 is the opening of the busy tone circuit at armature l0; and the opening ot the circuit of relay il at armature 48, whereupon relay 4.1 deenergiZes-to prepare the trunk tone circuit at armature 52, prepare the circuit oi relay 43 at armaresult of the deenergization ot relay 4,0 is

the opening of the circuit of switching relay 235 in series with stepping magnet 264 at armature 50,'Whereupon relay 235 deenergizes to open the circuit ot' the pilot lamp L4, Fig. ll; open the circuit of relay 262; and place ground on the contact in bank l; upon which wiper 200 is standing, as previously explained.

Anexplanation will now be given of' the operation should the calling subscribers line be a restricted service line. lt will be as sinned that the calling subscriberA is to be denied certain kinds ot service and that he has originated a call and that saidl call has been extended to an operators head telephone set O by Way of the individual line switch C and preselected relay trunk group R, already explained.y On subscribers lines having restricted service, a ground is placed on the restricted service bank springs, such as 25, at the individual line switch by means of a jumper Wire, such ol. I When the call is cut in to the operator a circuit may. be traced from ground, umper Wire 31, bank spring 25, contact 29, armature 79 and its Working contact, conductor 305, and red (no toll) lamp lf to grounded battery. rl`he lamp L2 will light to notity the operator that the line to which she is connected is a restricted service line. She Will then receive the order and either extend the connection byplugging it through or deny the service and so advise the subscriber who will restore his receiver. ln either eventI the circuit including the lamp L2 Will be broken in the Well known manner already explained and the lamp extinguished.

An explanation will. non7 be given of the operation shouldthe called subscriber be on the same line With the calling subscriber. 1t will be assume-:l that the subscriber at substation A Wishes to converse with the subscriber at il and that the former has removed his receiver' and caused the line switch C to plunge and seize the relay trunk group It. The connection willbeextended to the operator as previously explained, whereupon the olgierator will receive the order and pick up any idle cord circuit, such as E in this case,

and make the customary jack sleeve test.l

lWhen the ope ator touches the sleeve of jack l with the tip or" plug i3 a circuit will be closed which may be traced from ground, relay 307, conductor 340, resting Contact oit armature 161 and said armature, tip of plug P, sleeve et jack J, Fig. l, bank spring 24, contact 28, and armature 47 and its Working contact to grounded battery. Relay 3 07 Will energize over this circuit and close a revertive tone circuit Which extends from the revertive tone machine by Way of armature 309, conductor 230i, vworking Contact of armature 7l and said armature, Contact 28, spring 2li, sleeve oi jack J, tip et' plug P', armature lol and its restino' contact, conductor 340, condenser Sill, and left hand Winding of incuction coil .l to ground. The presence of the tone current in the lett-hand winding causes by induction a similar tone in the righthand winding et the induction coil I Which is audible to the operator. V rilhe operator upon hearing this tone will connect the calling party ,to a special operator Who Will complete the connection and the operators telephone head set and the storing equipment will become available for other calls in a manner similar to that. already explained. Upon termination of the conversation the equipment vwill restore to normal in the 1nan n already explained. Y.

An explanation will now be given of lthe operation should a trunk to an idle operator be seized by a line having a short, ground or any other class oi permanent thereon. lt will be assumed thata permanent exists on the line havingfthe substations A and A thereon, and that the connection is extended to the operators telephone `head set (l, by ivay of the Vline switch C and relay trunk `group lt, inthe manner already explained. The operator upon seeing the call lamp light ed, but linding the line unoccupied, realizes a cpermanent exists and momentarily depresses the common permanent key K. TWhen the key K depressed a circuit may be traced from ground, spring 322 and its Workingl contact, and magnet 340 to grounded batv tery. Magnet 346 energiaes over this circuit and causes the cpernninent and busy call meter N to operaie and register the call. A turther result o't the depressing of the key K is the closing of a circuit tor relay il traceable from ground, spring 323 and itsinner Working Contact, conductor 302, Working Contact of G9 and 71 by'ivay of armature 75 Vand said armature, and upper Windino` ot relay 41 to grounded battery. Relay 41 uponenergizing, closes a holding circuit tor itself at arniatiire by Way of ground at Working Contact of armature 48 and said armature. A further result of the ener- Agization otrelay 41 -is'the transferring of the holding ground for relayv 43 from 'arniature 64 to spring 323 at key K, at armature 54, the latter circuit being in multiple with the 'previously traced operating circuit of relayv 41'. A further result of the energization of relay 41 isthe preparation of a circuit orplacing ground on conductor 230 at armature 56, by Way of armaturev 67 and its resting contact, armature 50 and its Working contact, after relay 43 has deenergized and 'relay 44 has energized to actuate itsaiinature 7 2 as Will be explained hereinafter.

At the same time relay 41 is energizec, relay 42 is sliorted by a circuit traceable from ground, spring 323 et ley lt?, conductor 303, and working contact of armature armature, relay 42,` closed contacts at armature 49, to ground at the closed contact ot farinatiu'el (32.V Relay 42, upon deenergizing,

on conductor 102-leading to the of inder F, Fig. 2, and closes armature 60. The

places ground private bank a circuit for relay 44 at circuit-.for relay 44 may be traced troniy deenergization oit relay A42 isthe closing of a circuit ior the peinianentalarin signal at armature lrby Way of groi'ind at-theivorlring contact of armature 66 and said armature, which signal persists aslong as the operator holds therperinanent-ley K depressed and serves to indicate to the Wire-chier` the fact that a permanent7 exists onl sonie line. rlhifs permanent alarm signal would also serve to indicate tothe. ivire-chiel-the accidental locking up of relay 43, with no calls having seized the relay trunk group R, which would prevent the subsequent operation Vof the equipnicnt.V

[is a result ot the joint energization and deeiiergization ol relays 41 and 42, respectively, a trouble tone is connected to the release trunk leading to the sleeve oit the multiple `iacliil at armatures 53 and 59, respectively, traceable.

iti-:ornground at .the trouble tone equipment, Working contact or" armature 53 and said ariiiatui'e, armature and its resting contact, bank Contact 28,y and vspringf24 lto the sleeve ot the. viinrltiple jack J, Thistone persists until the troubleis-cieil and serves to pre- 7? .and said vent Wrong busy reports on succeeding calls for this line. A further result of the .joint energization and deenergization of relays 41 and 42, respectively, is the closing of a circuit ior the olf-normal signal lamp `at-arniatures 57 and'62, respectively, traceable from ground, armature` 62and its resting contact,

armature 57 and its Working contact,` through the oli-normal signal lamp to grounded battery. This lamp signal serves to indicateto the Wire. chief or attendant the'particular trunk Which is connected to theline upon y which the permanent l exists, sothat this line may easily be located.

Al/Vhen the lrey K is released the holding.

circuit of relay 43 is opened at spring 323.

VRelay 43, upondeenergizing, opens the circuitof relay 45 at armature 65; opens the circuit of the off-normal signal at armature 66,' removes ground from conductor 231 leading to the call assigner S3 by Way of Wiper' 233 of marker S at armature 64; and removes ground from conductor 230 extending to the marker S at armature 67 While said armature ispassing `from one Contact tothe other. Froinfthis it will be seenY that the operators telephone head-set 0 is .disconnected from the i relay trunlrgroup R, that the marker S is released While thecall assigner S3 is dissociated from the marker S', all of which become4 available for: further use as previously explained.

When the trouble on the line is cleared the line relay 40 deenergizes, whereupon the line switch isreleased in the manner already explained. A further result of the deenergization of relay 40 .is'the opening of the circuit ot relay 41 at armature 48. Relay 41, upon deenergizing, vpreynires the trunk tone circuit vat armature 52; opens the trouble tone circuit at armature 53; prepares the energizing. circuit of relay 43 at armature .54; an'd opens .thev circuit of theotl-normalr signal lamp and places ground on conductor 230 at armature 57; yllroin this it Will bc'seen that the apparatus of the relay trunk group R is restored to normal condition and'available for further use. f

An explanation Will now be given of the operation should there be one or more calls stored' upby the storing equipment When a call is originated vor when a call is coin aleted.

It ivill be assumed that Vthe subscriber at A originates a call and thatv itis received and marked by the marker S', byA Way ot line switch C and' trunk relay group R-,in the inanner already described. Relay 43 of ti'unli group R,'which causes relay 45 to connect the calling'subscriber'A with theoperator, cannot operate until the wiper 260 ot the call S? has reached Vthe contact in thev assigne-r bank B5 to whichv the relay isconnectel.

`When Wiper 260 reaches this contact relay v43 operates and causes theconnection to be extended to the operatorwhoreceives the order,

tests the called line, and sets up or denies the connection, as the case may require, whereupon the marker is released and the call assigner dissociated therefrom in the manner already explained. It there are calls in waiting relay 262 will be held energized over the common conductor 246 to cause the call assigner S3 to step its wiper forward, pick up and handle the next call in order regardless of whether the previous call was completed, or connected to busy or trouble' tone. Due to the idle. .markers beingfpreselected in rotation by the marker distributor it will be seen that the marking and storing equipn'ient automaticallyconnects the calls to the operators talking and listening circuit in the same order as they are originated.

An explanation will now be given ot the operation should the called subscriber desire to make a call before tl e operator has removed the plug from his multiple jack. For the purpose of explanation it will be assumed that a connection has been completed to substation A by means ot' the cord circuit E. lt will furthermore be assumed that both the calling and called subscribers have restored their receivers, the disconnect lanip L lighting as previously explained. It the called subscriber should remove his receiver before the operator has removed the plug from the multiple ack, line relay 18o i 7ill energize and close a circuit for the pull-in winding, which will in turn energize and cause the line switch C to plunge and seize a preselected relay trunk group, similar to R, as already explained in connection with line switch C. llVhen the line relay of the relay trunk group energizes, it connects battery to the junction 'of the hold-in winding 188 and sleeve of the jack J. Enough current will now flow in the hold-in winding 188 to energize it and hold theline switch in operated position, while a difference of potential will exist at the multiple jacks oit the line which is great enough to energize the busy test relay 307 when the operator touches the sleeve ot the jack with the tip ot'the plug.' Y

An explanation will now be given oit the operation should the operator fail to properly depress the ringing master key at the'time ot inserting the plug in the multiple ack of the called line. been cut in to the operator, whose telephone head set is shown at O, and she selects the idle cord circuit l@ to make the tests and completo the connection to the wanted subscriber A by inserting the plug P in the jack J'. lrilhen the plug is inserted in the jack a circuit will l be closed which. may be traced from ground,

lett hand winding of induction coil l, condens r 314, conductor 8&0, resting cont-actor varmature 161 and said armature, tip of plug P and jack J, and resting contact of spring y15 and said spring to the guard tone equipment as indicated. The presence of the tone lt will be assumed a call has current in the lett-hand winding causes by induction a similar tone in the right-hand winding ot the induction coil I, which is audible to the operator. T ie operator upon hearing this tone will properly depress the ringingI naster key, whereupon relay 1556 energizes in series with the cut-oil winding of the called line switch and the guard tone circuit is bro-ken.

ln order to explain the selective ringing circuits a little more in detail, it will be assumed that `the subscril er at substation A2 is being called by the subscriber at substation A, for instance, and that the cord circuit E is the one used. rlhe operator inserts the plug P in the jack J and since the bell of the called substation A2 is adjusted to respond.v to 50 cycle ringing current she will momentarily depress the corresponding common frequency selectin e; key lig. Upon pressing the key K3 a circuit is closed 'for magnet 3115, upper winding of relay 136, and holding winding 188 in series at spring 328, whereupon the .peg

count meter hl registers the completed call,

the relay 13G energizes to perform its functions, and the bridge cut-off armature 186 operates to disconnect the line relay 183 from the line, in the manner already explained. VAs a 'further result ot the depressing ot the key K3 a circuit is closed which may be traced irom ground, spring 327 and its working Contact, conductor 343, working contact of armature 166and said armature, resting contact of armature 160 and said armature, and relay 182, to grounded battery. Relay 132, upon energizing, closes a locking circuit for itself at armature 149 by way of ground at armature 162. vA further result oithe enerscribcr removes his receiver or the operator breaks the connection by pulling the plug, as already explained. The circuit ot rclay132 is opened at armature 162 when relay 136'is decnergizeil by the operator taking down the connection. `Relay 132 is thus restored to norn mal condition, as is also the other apparatus oit' the cord circuit E, and the cord circuit is available for further use. l

To call the subscriber at A, using the saine cord circuit E, the operator will momentarily depress the common frequency selecting key corresponding to the bell onthe line, in thisl case H2. U pon depressing the ,key l@ a circuit is closed again tor magnet 345, upper winding oi relay 1,36, vand holding winding 188 in series at spring 326, whereupon the peg count meter N registers the completed call, the relay 136 energizes to perform its `functions, and the bridge cut-oli? armature 186 lll() operates to disconnect the line relay 183 'from the line, as previously explained. As a further result of the depressing of the key K2 two circuits are closed simultaneously which may be traced asitollows: One circuit inay be traced from ground, spring 325 and its working contact, and conductor 343 to grounded battery by way ot relay 132 vand armatures 160 and 166.. Relay 132 energizesl and actuatesits armatures the same as explained in connection with the depressing of key K3. The other circuit may be traced from ground, spring 324 and its working contact, conductor 342, working contact of armature 165 and said armature, resting contact of yar-k mature 159 and-said armature, and relay 133 to grounded battery. Relay 133, upon energizing, closes alockino' circuitfor itself at armature 151 by way oi' ground at armature 162. A further resulto't the eneigization ot relay 133 is the actuation ot armaturek 152, which together with the actuation ot' armature 150 of relay 132closes the ringing circuit traceable as previously up to and including the armature 152 but now extended by way of its working contact, and 66 cycle generator G4 to grounded battery. This circuit is effective until the called subscriber removes his receiver or the operator breaks the connection by pulling the plug, as already explained. lThe circuits of relays 132 and 133 are opened at armature 162 when rea lay 136 is deenergized by the operator taking down the connection. Relays 132 and'133 are thus restored to normal condition, as 'is also the other apparatus of the cord circuit E, and the cord circuit is available for further use. a

To call the subscriber at A4, again using the same cord circuit 15 the operator will momentarily depress the common frequency selecting key corresponding to the bell on, the line, in this case-K5. Upon depressing the key K5 al circuit is closed as usual for magnet 345, upper winding of relay `136, and .holdingV winding 188 in series at spring 331, whereupon the peg count meter N" registers tbe completed call, the relay 136 energizes to perform its functions, and thebridge cut-.olf armature 186 operates to disconnect the line relay 183 from the line, as previously explained.' As a Vvfurther result oi' the depressing oi'i' the `key K5 a circuit is closed which may be traced iiroinc'round. s urine' 330 and its workin@ con- C 1 C 2D and 16 `cycle generator (Pto grounded bat-v tact, and conductor 342 to grounded battery vby way ot relay 133and armatures 159and 165. Relay 133 energizes and actuatesits armatures the saine as explained in connection with the depressing oit key K2, only armaturel 150 is not actuated at this time and armaturel 153 closes the rinOinO circuit traceableas areviously up to and including this armature but now extended by way or its working contact,

terj. This circuit is effective until the called subscriber removes his receiver or the operatorbreaks the connection by pulling the plug, as already explained. Relay 133, as

well as the other apparatus ofv the cord cir-A ing circuits, that the provision of the two step ,relay`135 is what makes it possible to use the common ringing current selecting keys K?, K3, etc. rather than keys'individual to each cord circuit. When any ringing key such as K2 is depressed relay 135 operates in its first step along with relay 136,*and when such key is released relay 135 operates in its second step. On completely operating, relay 135 opens the initial energizing circuits of selecting relays 13,2 and 133 at armatures 159 and 160, therebypreventing any false operation when a key is later operated to control the ringing current selection at another cord circuit. y

. An explanation will now be given of theoperation should the operator, using the telephone head set O, Fig. 4, vacate her` position.

lVhen she removes the plug P2 from the jack J2th'e circuit including the operators trans-v initter, the right-hand windings of the induction coil I and the relay 308 is broken. Relay 308, upon deenergizing, releases the armatures 311, 312 and 313, whereupon battery potential is placed on the contacts of masten switch bank B0 corresponding to all relay trunk groups, such as R, assigned to that particular operators posit-ion. It will be seen that arinaturesf311 and 312 are connected to contacts in bank B0 of master-switch M, by

- way of conductors 209 and 204, respectively,

while armature 313 is connected to a contact in another master switch bank; also it will be understood that there may be other armatures similarly connected. Should the master switch wiper 220 now be vrotated to the contact in bank B0, to which the conductor 209 is connected, a circuitis closed traceable from ground, lower winding of relay 215, wiper 220, conductor 209, and working Contact of armature 311 and said-armature to grounded battery. Relay 215 will energize over this Vcircuit and cause the master switch M to im@ inediately rotate to the nextcontact, or until one isy found not having battery potential thereon, in the manner already explained.

From this it will be seen that an voperator can leave her position and busypit toy all incoming calls by nierely removing her telephone headset plug from the ack.

Having described my invention, what I :consider to be new and desirepto have vpro-- tected by Letters Patent will be pointedout in the appendedclaimsl icc l CII lVhat is claimed is:

l. In a call distributing system, trunk circuits, automatic switches responsive to the initiation oit calls'for extending the calling lines to idle trunk circuits, an operators switchboard, and means including sorting devices for connecting trunk circuits upon which calls are waiting to the operators head set in the enactV order in which such trunk circuits are connected with.

2. In a call distributing system, trunk circuits, automatic switches responsive to the initiation of calls for extending the calling lines 'to idle trunk circuits,` an operators switchboard, means including sorting devices for connecting trunk circuits upon which calls are waiting to the operators head set in the exact order in which such trunk circuits are connected with, and a visual signal at said switchboard operated automatically when any trunk circuit is connected to said head set.

3. In a call distriln'iting` system, trunk circuits, automatic switches responsive to the initiation oit calls 'for extending the calling lines to idle trunk circuits, an operators switchioard, means including sorting devices for connecting trunk circuits upon which calls are waiting to the operator-s head Set in the exact order in which such trunk circuit-s are connected with, and means including a bank of signals at said switchboard for indicating the number of waiting calls.

Ll. In a telephone exchange system, a plurality of subscribers lines, a plurality oit trunks, means whereby any one oit said lines can be automatically connected to an idle one of said trunks upon a call being originated, means eilective responsive to the operation of the rst named means for automatically extending said trunk to an idle operator, means including an automatic switch whereby the operator can complete the connection to the called subscribers line, and means whereby the called party can originate a call to an idle operator immediatelyafter he and the calling party have hung up and before the previous connection taken down.

5. In a telephoneexchange system, a plurality oi line switch and jack ending subscribers7 lines, a plurality ot trunks, means whereby any one oit said lines can be automatically connected 'to an idle one ot said trunks upon a call being originated, means etl'ectivc responsive to the operation et the iirst named means for automatically extending said trunk to an idle operator, means whereby thc/Operator Vcan complete the connection, and means whereby the sleeves oli both the calling and called partys multiple jacks willtest non-busy toY Vcalls for those lines immediately after the calling and called i parties have hung up and before the connection has been taken down.

6. In a telephone system, ymeans including an automatic switch and a cord circuit 'for connecting a calling and a called line, means including a key for placing test potential upon the sleeves of the jacks associated with the connected called line, means cont-rolled by the calling subscriber 'for releasing said switch, and means under the joint control of the calling and called subscribers for reioving said busy potential while the cord circuit remains connected to the called line.

7. In a telephone syst-em, means including an automatic switch and a cerd circuit individual to said switch for connecting a calling and a called line, a cut-off relay `for the called line energized over the sleeve of said cord, means responsive to the hanging up et the receiver by the calling subscriber i'or releasing said switch, and means responsive to the hanging up of the receivers by Aboth subscribers 'for deenergizing said relay.

8. In a telephone system, means including an automatic switch and acord circuit for connecting a calling and a called line, a cutoil' relay for the called line energized over the sleeve of said cord, means responsive to the hanging up oit the receiver by the calling party for releasing said switch, and means responsive to lthe hanging up of the receivers by both subscribers for deenergizing said relay, said last means comprising circuit arrangements in the said cord circuit for inserting a resistance in the sleeve circuit thereof to cause said cut-oil relay to deenergize as set forth. Y

9. In a telephone system, means including a cord circuit for connecting a calling and a called line, a cutoff relay for thercalled line and a sleeve relay in said cord circuit energized in series, said sleeve relay havingV two windings one oit' which is normally sliort'circuited, and means responsive to the replacenient 'of the receiver vat both calling and called stations for removing said short circuit, thereby increasing tlic resistance of the sleeve circuit sufficiently to deenergize sait cut-oill relay.

10. In a call distributingsystem, trunkA circuits, cord circuits, means responsib to the initiation of a call 'for connecting the calling line to an idle trunk circiut at one ond thereof, and means responsive lo. the act ot' ringing the called party after one or" said cord circuits has been plugged into the called line `tor connecting the cord circuit in use with the connected trunk circuit the other end thereof. 1

l1. In a call distributing system, trunk circuits, cord circuits, means responsive to the initiation or" a call for connecting-the calling line to an idle trunk circuit at one' endv thereof, finder switches individual to. said cord circuits, respectively, and operator Controlled means effective only after one ot'said cord circuits has been plugged into the called line for starting the associated iinder in search of the trunk circuit to which the call-` cuits, cord circuits Vtor completing ccnnections to called lines, and iinder switches indi-- vidual to the cord circuits for connecting them with said trunk circuits. y

13. In a call distributing system, trunk circuits, line switches responsive to calls toil connecting calling lines to said trunk circuits, cord circuits for completing connections to called lines, tinder switches iiidividual to said cord circuits, and means 'for causing the tinder associated with any cord circuit in use to connect such cord circuit with the particular trunk circuit to which the calling line is connected.

14;. In a call distributing system, trunk circuits, automatic switches for extending calle ing lines to said trunk circuits, means for eX- tending connected trunk circuits to the oper ator one at a time, multiple jacks associated with said lines, and Operator controlled means in each trunk circuit for placing a distinctive tone on the sleeves of the multiple jacks associated with the connected line.

l5. In a call distributing system, trunk circuits, automatic switches or extending calling lines to said trunk circuits, means for extending connected trunk circuits tothe operator one at a time, multiple jacks associated with said lines, a trouble tone relay in each trunk circuitfor placing a distinctive tone on the multiple jacks of any connected line, and circuits over which the operator controlls said relays. y

16. In a call distributing system, ine-ans incliiding an automatic switch for extending a calling line to an operator, inult-iple jacks associated with the calling line, a cord circuit 'toi' use in testing the called line and for eX- tending theconnection thereto, a` test relay ase sociated with the operators head set, acircuit for said relay including the Atip oi saidcord,

means controlled by said relay for placing a distinctive tone onthe multiple acks of 'the calling line through contacts of said switch,

and an inductive connection between-the cir.

cuit of said test relay and the operators head set circuit, whereby in case the called line is .the same as the calling line the'operator will hear said tone when she touches one-0f` saidjacks with the tip of said cord.

17. In atelephone exchange system, a plurality of line switch and jack ending subscribers lines, a plurality of relayt'runk groups,

means whereby any one of saidrlines can'be' automatically connectedA to an idle one of said trunks upon a call being originated, means for automatically extending said trunk to an idle operator, a plurality of plug and iinder Y switch ending cord circuits whereby the operator can set up the connection by inserting the plug of any one of said cords in the jack of the wanted line, a plurality of ringing keys, a guard tone machine, and means whereby the operator instantly receives a guard tone from said machine upon failure to properly depress one of-said keys at the time of inserting aidplug inthe multiple jack of the called ine. i

18. In a telephone system, cord circuits for use in connecting calling and called lines,

' ringing current selection control keys, and

means for audibly signaling the operator in case -she plugs one of said cord circuits into a called line without having first operated one ot said keys. i

19. In a telephone system, cord circuits forv use in connecting calling and called lines,

ringing current selection control keys, ringing current selecting relays in each cord circuit controlled by said keys, and mean-s for signalling the operator in case she plugs one of said cord circuits into a called line without having first set said selecting relays by operating one of said keys.

20. In a cord circuit, a'` ringing current selecting relay, a sleeve relay energized when the cord is connected to a called line, ringing current selection control keys, a relay in said cord operated responsive to Ythe actuation and restoration of one of said keys, and a circuit for said selecting relay controlled jointly by the other of said relays.

2l. In acoid circuit, a ringing current selecting-relay, a sleeve relay energized when the cord' is connected to a called line, ringing current selection control keys, aerelay in said lays in each cordv circuit, ringing current y selection control keys common to said cord circuits, circuits u/'lier'eby said keys control the selectag relays in all said cord'circuits, and means in each coid circuit "in use for removingthe associated selectingrelays from the control of said keys responsive to the restoration oiC an operated one of said keys.

In a telephone systen'na cord circuit for connecting with a called line, a cut off relay for said line', a sleeve relay in said cord, a ringing key, and .an initialenergizing circuit for both said relays in series closed by the actuation of said key.

24k. In a telephone system, a cord circuit Jor connecting with a called line, a cut olf relay'ipor said line, a sleeve relay in said cord, ringing current selecting means in said cord, keys fork centrolling said means, and

trolled by said relay.

an energizing circuit for said relays also controlled by said keys.

In combination, a cord circuit, an operators head set, a Vnormally closed test circuit extending to said head set from the tip ot .said cord, a relay for opening said test circuit, a ringing key, and a circuit for said relay closed bythe actuation of said ltey.l

26. ln a telephone system, a cord circuit lor use in connecting a calling and called line, a two step relay in said cord circuit operated in its iirst stage responsive to the connection oi? said cord circuit with the calling line, circuit arrangements for operating said relay in its second stage responsive to the replacement ot the receiver at the calling station, and a supeiyisory signal ,controlled by said relay.

27. ln a telephone system, a cord circuit tor use in connecting a calling and called line,

a two .step relay in said cord circuit operatedV in its iirst stage responsive to the connection of said cord circuit with the calling line, circuit arrangements for operating said relay in its, second stage responsive to the replacenient of the receiver at the calling station, and a circuit for` signalling the called line con- 28. In a telephone system, a cord circus;

tor use in connecting a calling and called` line, a two step relay in said cord circuit operated in its irst stage responsive to the connection ol said cord circuit with the calling line, circuit arrangements 'for operating said relay in its second stage responsive to the replacement ot the receiver at the calling station, a circuit for signalling the called line controlled by said relay, a ring cut olf relay, and a locking circuit for said ring cut oil relay also controlled by said two step relay.

29. In a telephone system, a cord circuit for use in connecting a calling and called line, a two step relay in said cord circuit operated in its iirst stage responsive to the conne-"ion of said cord circuit with the callii line, circuit arrangements for operating said relay in its second stage responsive to the replacement ot the receiver at the calling station, a signalling circuit, a ring'cutoli relay, and an initial energizing circuit for said ring` cut-ott relay controlled by said two step relay in the second stage of its operation.

BO. ln a telephone system, a cord circuit tor use in connecting a calling and called line, a two step relay in said cord circuit operated in its first stage responsive to the connection of said cord circuit with the cally ing line, circuit arrangements tor operating controlled by said two step relay in the second stage of its operation.

3l. In a telephone system, a cord circuit.

tor use in connecting a calling and called line, a two step relay in said cord circuit operated in its lirst stage responsive to the connection of said cord circuit with the calling line, circuit arrangements ytor operating said relay in -its'second stage responsive to the replacement or" the receiver at the calling station, a double wound sleeve relayin said cord circuit energized in series vwith the cut oit relay ot the called line, and a shunt for one winding ot said sleeve relay controlled by said two step relay.

32. ln a telephone system, a cord circuit tor use in connecting a calling and'called line,

a two step relay in said cord circuit operated double wound sleeve relay in said cord circuit i energized in series with the cut-oit relay ot the called line, a battery teed relay in Vbridge oit the cord, contact on said two step relay included in said bridge, and a shunt for one winding of said sleeve relay controlled jointly by said two step relay and said battery feed relay. Y

33. In a telephone system, a cord circuit for use in connecting a calling and called line, a two step relay in said cord circuit operated in it-s irst stage responsive to the connection of said cord circuit with the calling line, circuit arrangements for operating said relay in its second stage responsive to the replacement of the receiver at the calling station, a sleeve re- 1 lay energized in series with the cut-ott relay ot the called line, a battery feed relay in bridge of said cord circuit, and means jointly controlled by said two step relay and said battery feed relay for increasing the resistcord to one pole ot the exchange batteryV including one windingot said relay and a pairY ot contacts operated bythe relay armature,

and a connection from the other talking strand or the cord to the other pole oiE said battery including the other winding otl said relay andV another pairot contacts operated by the relay armature.

35. lin a cord circuit ior use inconnecting a calling and called line, a relay, a second re-` lay connected in bridge ot the talking strands at the called end ot the cord in series with a battery, the connection including contacts ot said first relay, contacts on said second relay for shunting the said contacts on said first relay when the second relay is energized over the called line, and meansresponsive to the replacement of the receiver at the calling station for energizing said iirst relayto open its said contacts. v

36. In a telephone exchange system, a plus rality of lineswitch and jack ending subscribers lines, the jacks oit lsaid lines having tyvo talking terminals and a sleeve terminal, a plurality of trunks, means lfoi automatically operating the lineswitch associated With a calling line to connect said line to an idle one 01"' said trunks, operator controlled means for completing the connection, and means Whereby the sleeve terminals of both calling and called parties multiple jacks will test nonbusy te calls -for those lines immediately atteitlie calling and called parties have hung up their receivers and before the connection has been taken down. y

37. In combination, a cord circuit, an operators head set, a test circuit extending to said head set from the tip oi said cord, a ringing key, a relay tor opening said circuit opn erative responsive to the actuation ot' saidkey, said circuit including normally closed contacts on said relay, and a. locking circuit for said relay.

38. ln combination, accord circuit, an operators head set, a test circuit extending' to said head set from the tip of said cord, a ringing key, means controlled by said key for opening said test circuit and a link in the talking circuit, and means for maintaining` said nrst means operated independent otsaid key. i

39. ln' a call distributing system, trunk lines, means including an automatic switchv or connecting a calling line to a trunk line, operators circuit, means for extending the connected trunk line to said circuit, and operator controlled means or'disconnecting the connected trunk line 'from said circuit and vtor locking said automatic switch in posit-ion.

fit). ln a call distributing system, trunk lines, means including an. automatic switch for connecting a calling line to a 'trunk line, an operatoi"s'circuit, means 'tor extending the connected trunk line to said circuit, operator controlled means 'toi' disconnecting the Vconnected trunk line from said 'circuit and for locking said automatic switch in position, and

a signal operated responsive to said auto-r matic switch being locked. n lil. ln a telephone system, a

icc/tive responsive to the removal of the receiver at a subscribers station terminating a line 'to connect one end of the trunk to that line, a plurality ot plug ending cord circuits,

.automatic switching` mechanism effective resubscribers lines, a plurality of cord circuits,

for completingv plurality of. subscribers lines, a trunk circuit, means ef-V a plurality oit trunk circuits, each trunk for connecting any line With any cord, a signal,

means responsive to the removal of the re ceiver at a subscribers station terminating a line to connect that line to an idle trunk and to operate said signal, and meanseifective responsive to the taking of any cord into use to connect said cord with ythe selected trunk and to release said signal.

in a telephone system, a plurality or" trunks, an operators head set, automatic selecting mechanism effect-ive responsive to the taking oi'f a trunk into use to connect said operators set to the trunk, a plurality of cord circuits and means ciiective responsive tothe operator taking any cord circuit into use for connecting the coidfto the trunk to which the operaters set-is connectedv and disconnecting the head set.

44. In a telephone system, a plurality oit trunks, an operaters head set, automatic selecting mechanism having a receiving position for each oi' said trunks adapted under predetermined conditions to connect said operatorssetto any trunk, a plurality of cord circuits, and means eilective responsive to the operator taking any cord circuit into use for connecting the cord to thetrunk to which the operators head set is connected and disconnecting the head set. c

45. ln a telephone system, a group 'of trunks, means for seizing idle trunks of the group in a certain order, an operators head set, automatic selecting mecha-A nism having a receiving position for each of said trunks adapted to successively cause the connection of rsaid operators set to cer- "tain seized trunks in thesame order as the vtrunks are seized, said connection excluding the said receiving'position of the trunk in the selecting mechanism, means effective re- Y sponsive to the connection ot thejoperators headset to one oi' the trunks to stop the fur-A 'lier operation of tlie'm'echanism, and means under the control of the operator tor disconnecting the headset from the trunk to.A

which it is connected and reinitiating said automatic selecting mechanism into operation. i

d6. ln a telephone system, a group of Y trunks, means for seizing` idle trunks of the group in a certain order, an operators head set, automatic selecting mechanism having a receiving position for each ot' said trunks Aadapted to successively connect said oper-k ators set to seized trunks in the saine order as the trunks are seized, means effective responsive to theiconnection of the operators set to one ot the trunks to stop the urther operation ot the mechanism, a plurality of cord circuits, means automatically effectiveA responsive to the operator taking anycord circuit into use Jfor connecting the coid to the trunk to which the operators head set is connected, disconnecting the head set from 'for cenneeting a. callingn line i0 a called line,

means ei'l'ecive when the plug of a cord is inserted into he yacl; of a called line to render the called line-busy,v means in each cord linitiated in its operation when a Connection .is establiehed from a. calling line te the Cord and fully operated when the call is terminated by the calling party to render the called line idle under predetermined conditions regardless of the presence of the plug in the jack of the line.

i-8. In combination, a cord circuit, ar ring ing key, and a' relay individual to said cord Win74@ circuit energized over a circuit including Contact on the key in'series With the sleeve of Jche cord'.

49. In a telephone system, a plurality'ef Cord eireuite, an eperalers head set, a test lcircuit exending to said head set, said circuit including' a plurality el biancheseach.

of which is nern'iallyreennectedto one of said cord circuits, and a relay in each cord circuit for opening the associated branch, a ringing key, and a circuit for operating any unoperated relay 0l any Co-rd over which a call has been extended, said circuit being efe rtive responsive to the operation of the key.

11i Witness "whereof, I hereunto `subscrib iny naine.

JOHN eeTLiNn.

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