US1502917A

US1502917A - Interoffice trunking system

Info

Publication number: US1502917A
Application number: US428225A
Authority: US
Inventors: Winfred T Powell
Original assignee: STROMBERG CARLSON TELEPHONE
Current assignee: STROMBERG CARLSON TELEPHONE; STROMBERGCARLSON TELEPHONE MANUFACTURING Co
Priority date: 1920-12-04
Filing date: 1920-12-04
Publication date: 1924-07-29
Anticipated expiration: 1941-07-29
Also published as: USRE17839E

Description

nmy 29, 1924.,

W. T. POWELL INTEROFFICE TRUNKING SYSTEM Juiy 29. 1924. v

W. T. POWELL INTEROFFICE TRUNKING SYSTEM INVENTOR WINFRED T POWELL ATTORNEY Filed 1,502,917 W. T. POWELL INTEROFFICE TRUNKING SYSTEM Filed Dec. 4, 1920 4 Sheets-Sheet 5 ATTORNEY INVENTOR WIHFRED T POWELL Q@ i n s wa IUI I@ #Wim Fl July 29' 1924- july 29, 1924.

W. T. POWELL INTEROFFICE TRUNKING SYSTEM' Filed Dec.- 4. 1920 4 Sheets-Sheet 4 INVENTOR WIHFRED TPOWELL,

BY 9 ATTORNEY and more particularly to systems having a GN TELEPHONE MANUFACTURING CO'MPNY, 0F ROCHESTER, NEW YO CORPORATION OF NEW YORK.

Immersion 'murmure erstma Application filed December e, 1920. Serial No. 428,225.

To all whom t may concern.'

Be it known that I, WINFREn T. lownm., a citizen of theUnited States, res1d1ng at ing at different exchanges or oces without the use of the s o-called order or instruction telephone c1rcu1ts between the operators at Rochester, in the county of Monroe and \said exchan es.'

State of New York, have invented certain `new and useful Improvements in Interoiice Trunking' Systems, of which the following is a full, clear, concise, and exact description. v vThis invention relates to telephone systems plurality of oiiices or exchanges.

' In former telephone systems, when calls originated in one office for a subscriber at a distant oiice, an' operator known as an A operator, connected the answering end of her cord circuitV to the line of the calling subscriber and received thedesignation of the wanted line from this subscriber. The lAoperator then depressed an oliice key by which her telephone set was connected to an order` Wire leading to the distant wanted ofiice over which wire the A. operator repeated the number of the wanted subscriber to a B operator at the distant oiice who assigned a trunk for use in completing this call. The A operator then inserted the calling end of her cord circuit into the jack of the assigned trunk. The B operator after receiving the number of the wantedv line proceeded to test-this line and, if idle, inserted the calling end of her cord circuit into the. multiple jack of the wanted line and signalled the wanted subscriber. The use of suchan order wire has resulted in much delay and great confusion resulting from the errors due to repeating the number thereover.

The present invention has for its purpose the elimination of the order wire and provides in its stead automatic means for assigning an idle trunk to the distant oilice as `the result of the operation of an oiiice key and automatic means indicates visually the designation of the automatically selected trunk, so that the A operator can'connect the calling end of her cord circuit to the assigned trunk. At thedistant office the B operator is informed of the number of the wanted line by means of signals variably operated from the A operators position.

The main-feature of this invention is the arrangement of circuits for the manual interconnection of subscribers lines terminat- Another eature of this invention is the provision-.of means for automatically assigning an ldle trunk to a wanted exchan e in response tothe operation of a key individual -to said oliice and means for automatically indicating the trunk assigned. Another feature 'of the invention resides 1n the means for registering the designation of la wanted line on registering means located at one office and for automatically repeatlng such registration at a distant oilice to varlably and selectively actuate indicating means at the distant oice. y

Other features will appear'from the detailed description and appended claims. The drawings, with Figures 1, 2 and 3 arranged in the order named and with Fig. 4 placed below Figs. 1 and 2 so that the lines thereof meet, diagrammatically represent a portion of a telephone system employing the present invention. The circuits, shown on Fig. 1 and at the left of the heavy dotted lineof Fig. 2 and the circuits of Fig. 4f, representa portion ofthe equipment locatedat one oiice while that portion of the drawings at 'the right of the heavy dotted line of Fig. 2 and those shown in Fig. 3 represent the circuits of a second lofiice. At the upper left-hand corner of Fig. 1 there is represented the sub-station circuits of a calling subscriber as well-as a portion of an A operators cord circuit. At the lower lefthand corner of Fig. 1 there isrepresented a set of ten numerical keys and it is to be understood that there is one set of these keys at each operators position. At the middle and upper portion of the4 sheet of Fig..1 there is represented a switch referred to as a link finder of which there is one such switch for each oiice key at each operators position. At the center and right of FigiJ 1 there is represented a trunk finder switch and a sender finder switch, the brushes of which are connected together by a circuit referred toas a link circuit which link is located by the link finder. The trunk finder functions to select an idle one of a group of trunks to the wante cnice, while the sender finder locates a sender of the common oup of senders which has been preselected y a preselector switch shown at the bottom of Fig. 1. At the lower right-hand corner of Fig. 1 and the left-hand corner of Fig. 2 there is represented a progressively movable switch, herein referred toas a sender switch, while in the lower part of Fig. 1 and in Fig. 4 there are shown the relay registers for storing up the designation of the thousands, hundreds, tens, units and stations designations. At the upper left-hand corner of Fig. 2 there is shown a portion of an indicating board common to a plurality of operators positions and of which there is one such board for each office reached from the first mentioned ofiice. On this board there are located a plurality of lamps for indicating the tens and units designation of an automatically assigned trunk to a Wanted oiiice. At the center of Fig. 2 there appears a progressively movable switch, lherein referred to as a receiver switch and at the upper portion of Figs. 2 and 3, there appears a representation of the B operators cord circuit, while at the lower part of Figs. 2 and 3 there is represented the line indicator lamps and the relays for controlling the same.

It will be understood that the number of trunks such as that shown at the upper portion of Figs. 1 and 2 will 'vary in accordance with the traiiic between the various offices, similarly the number of senders for the ilse of all A operators positions located at the same oiiice will depend on the number of simultaneous calls therefrom.

It is believed that the invention will best be understood by describing the method of operation employed in establishing a telephone connection from the sub-station of a calling subscriber indicated at A to the sub-station of a wanted subscriber, "B, whose telephone line terminates in another exchange herein designated Main. When the calling subscriber removes his receiver from its switch hook, the line relay 5 is operated in the well known manner to light the line lamp 6. The A operator then inserts the plug 7 into the multiple jack 8 of the calling line which is effective to operate the cut-off relay 9 and this relay in turn disconnects the line relay 5 to extinguish the line lamp 6. The answering supervisory relay 10 of the cord circuit taken for use is also operated in this portion of the operators cord circuit which is not shown complete, since it may be of any well known arrangment. The A operators telephone set (not shown) is then connected to the calling line, either manually by listening key 11, as indicated, or it may be connected to the calling line through the operation of well known automatic connecting means so that the operator may inquire the designation of the wanted subscribers line.

For purposes of this description, it has armatures as the result of the closure of this circuit and closes a locking circuit for itself from ground at its inner upper armature and front contact, its lower winding, continuity spring and contact of relay 18, contacts of wipe-out key 19, winding of relay 14, armature, back contact and winding of the motor magnet of the sender preselector to grounded battery. y

The motor magnet will not operate in series with the mentioned relays. but the relay 14 is actuated and the relay 17 isheld operated in the last described circuit. As soon as relay 14 operates, it closes multiple actuating circuits for relay 21 which con nects the operators numerical key set to the preselected sender and the key set lamp 22 which indicates this connection. These circuits extend from grounded battery, winding of relay 21, lower front contact and armature of relay 14, back contact and armature of relay 13 to ground. The lighting of the key set lamp 22 indicates to the operator that the digits keys appearing at the lower left-hand corner of Figure 1 may he operated in accordance with the designation of the wanted number. The operation of relay 14 also closes a circuit for actuating relays 23 and 25 in series. this circuit extending from ground. winding of relay 23. upper front contact and armature ot relay 14. sender preselector brush 24 and winding of' relay 25 to grounded battery. The operation of relay 25 closes at its armature and front contact, a circuit from ground over conduo tor 31, armature and back contacts of relay 32 and the switching relays 27, 28. 29 and of the stations units` tens and hundreds registers, over conductor 33. right-hand winding of the thousands register switching relay 26, conductor 34, to grounded battery for actuating relay 26.

When relay 17 attracts itsl armatures, the operating and test circuits of the link finder. individual to 'the group of trunks assigned to the Main oiiice, are closed. The operating circuit for the link finder is closed from grounded battery. resistance, armature and cont-act 124 of relay 17, back contact. armature and winding of motor magnet 42, continuity spring and back contact of relay 40 to ground, and advances the link finder brushes until an idle link circuit is reached. whereupon the test circuit is completed from.

. ot` an idle link circuit.

neef/reir ground at the make-busy relay 36, righthand back contact and armature of relay 37, conductor 38, back contact and armature of relay 39. test brush 35, right-hand winding ot' relay 40, front-contact and armature of relay 17. conductor 41, resistance to gounded battery. This last named circ-uit is effective to shunt the motor magnet 42 of the link finder which then stops its

brushes

43, 44, 35 and 45 in engagement with the terminals erated in the last described circuit and closes a locking circuit for vitself from ground, winding of relay 39, holding brush 45 of the link finder, left-hand high resistance winding of relay 40, its innerarmatune and continuity spring, winding of the motor magnet 42, its armature and back contact, lower frontl Contact 124 and armature of relay 17, conductor 41and resistance to grounded battery, The operation of relay 39 renders the chosen link unselectable.

'Also when the relay 39 is operated, it closes operating circuits for the trunk finder switch and for the sender finder switch, the

first of these switches being advanced in a circuit completed from ground, up er contact and continuity spring of relay 4 winding of motor magnet 48 of the trunk finder, its armature and back contact, inner front contacty and armature of relay 39, outer back contact and armature of relay 37, through the resistance to grounded battery. vUnder the control of this circuit, the trunk finder t switch advances its

brushes

50, 51, 52, 53

and 54. until its test brush 54 engages a test terminal having ground potential applied at the left-hand armature and back contact of relay 55 whereupon the circuit is closed through the lower winding of relay 47, front Contact, and armature of relay 39, back contact and armature of relay 37, resistance to grounded battery.

, This circuit is effective to stop the trunk finder and also to energize the relay 47 which thereupon closes a locking circuit for itself from ground at the armature and back contact of a relay similar to 55 at another trunk over the multiple connection 218, left-hand winding of relay 55, holding brush 53, high resistance winding of relay 47, its upper armature and continuity spring, winding of motor magnet 48, its armature and back contact, to grounded battery, through the contacts and armatures of relays 39 and 37, as previously described.

In the event that all the trunks leading from the terminals of a trunk finde-r are busy, all the relays such as 55 of this group of trunks will be operated, thus removing the short-circuit from the common makebusy relay 36, permitting this last named relay to operate and disconnect the stopping ground potential from all the test terminals at the link finder switches, thus The relay 40 is oppreventing an link finder from selecting a linkV circuit aving no available outgoing trunk at the trunk finder switch.

The operating circuit of the sender finder is traceable from grounded battery through the resistance, outer right-hand armature and front contact of relay 39, back contact,

armature and windin of the motor magnet 56 of the sender fin er, continuity spring and contact of relay 57 to ground. This last described circuit causes the motor magnet 56 of 'the' sender finderv to advance brushes 58,' 59, 60, 61 and 62 of this switch until it reaches the same sender to which the key set is connected by 'way of the pre-` selector switch. At this time, ground at the armature and front contact of relay 23 is extended throughy brush 64 of the sender preselector, test brush 62 of the sender finder, upper winding of relay 57, outer righthand front contact and armature of relay 39 and resistance to grounded battery. The relay 57 is thus actuated and at its lower contact and continuit spring opensv the energizing circuit Iof t e motor magnet 56 and instead closes a circuit from grounded battery, outer armature and front contact of' relay 37, back contact armature and Winding of motor magnet 56, continuity sprin `and armature of relay 57, through the hig resistance Winding of this relay, holding brush 61 of the sender inder, winding of relay 65 to ground. The operation of relay 65 closes an actuating circuit for relay 25l lattracted its armatures to connect the set of numerical keys to the registers. The apparatus is now in condition to receive the designation of the wanted telephone line. Since it has been assumed that the wanted numberis 7764-R, the operator will thereupon depress the No.7 numerical key of the key set to close a circuit from ground, spring contacts 75, conductor 76, innermost lower armature and front contact of relay 21, brush 77 of the sender preselector switch, left-hand armature and front contact of relay 26, lower winding of the sensitive relay 78 and lower winding of the marginal relay 79, winding of relay 80, to grounded battery. Relays 78, 79 and 80 all operate in series and the first two mentioned relays close locking circuits through their upper lil windings, front contacts and armatures, through conductor 31, front contact and armature of relay 25, to ground. The o eration of relay 80 closes an energizing circuit for the relay 81 from battery, through its right-hand winding and through the armature and continuity spring of relay 80, to ground. Relay 81 then closes a locking circuit through the left Winding of relay 26 to grounded battery over conductor 34. When the No. 7 key is released, relay 80 retracts its armature and thereby closes a holding circuit for relay 81 which extends from ground at the continuity spring and contact of relay 80, left-hand winding, front contact and armature of relay 81, armature 82 and front contact of relay 26, right-hand winding of the hundreds register switching relay 30 to grounded battery for operating this relay. The primary locking circuit for relay 30 extends from grounded battery, left-hand winding, front contact and armature of relay 30, conductor 83, to ground at armature and contact of relay 81. The relay 30 on operating closes a second locking circuit for itself from grounded battery, through its right-hand winding, front contact and armature and through the back contacts and armature of

relays

29, 28, 27 and 32, over conductor 31 to the holding ground at the armature and front contact of relay 25. This last described circuit also is effective to short-circuit the left-hand winding of relay 81, so that this lastnamed relay deenergizes and retracts its armatures. The deenergization of relay 81 opens the holding circuit for the thousands register switching relay 26 which extended through the left-hand winding, front contact and armature, to ground at relay 81. The switching relay 26 thereupon deenergizes and disconnects the thousands register relays from the control of the numerical key set, butl relay 30 has already eX- tended this key set to the four relays of the hundreds register. Since the hundreds digit of the wanted number is 7, the operator again depresses key No. 7 to close a circuit from ground, key contactl 75, conductor 76, inner lower armature and front contact of relay 21, sender preselector brush 77, conductor 93, armature 86 and front contact of relay 30, lower windings of sensitive relay 87 and marginal relay 88, winding of relay 80. to grounded battery. Relays 87, 88 and 80 are operated and the register relays 87 and 88 close locking circuits through their upper windings, front contacts and armatures over conductor 31, to ground at the contact and armature of relay 25. When key No. 7 is released, relay 80 deenergizes and again completes a locking circuit for relay 81 (which was energized simultaneously with relay 80) from ground at the continuity spring and contact of relay 80,

winding of relay 81, its front contact and armature, armature 82 and back contact of switching relay 26, armature 88 and front contact of relay 30, right-hand Winding of thel tens register switching relay 29 to grounded battery. The switching relay 29 attracts its armatures and closes two locking circuits for itself; the first extended from grounded battery, through its lefthand winding, front contact and armature, conductor 83, outer armature and front contact of relay 81 to ground, which circuit insures that the relay 29 will be held by its second locking circuit including its righthand winding, front contact and armature through the back contacts and armatures of relays 28, 27 and 32 over conductor 31, to ground. The tens register is now in condition to beA adjusted in accordance with the tens digit of the wanted number which in the case assumed is 6. The operator thereupon depresses key 6 to close one circuit from ground, through the resistance, key contacts 90, conductor 76, innermost armature and front contact of relay 21, sender preselector brush 77, conductor 93, armature 94 and front contact of relay 29, lower windings of the sensitive register relay 95 and marginal relay 96, through the winding of relay 80, to grounded battery. The sensitive relay 95 and the relay 80 are energized in this series circuit but the marginal relay 96 remains inert. On the operation of relay 95, a locking circuit is closed through its upper winding, front contact and armature, over conductor 31 to the holding ground. When the operator depresses numerical key No. 6, a second circuit is closed from ground resistance, key contacts 90, conductor 91, lowermost armature and front contact of relay 21, sender preselector brush 92, conductor 85, outermost armature and front contact of the tens switching relay 29, upper windings of the sensitive re- -lay 227 and marginal relay 228, conductor 103, to grounded battery through the winding of relay 80. The marginal relay 228 does not operate in the circuit but the sensitive relay 227 is energized and closes a locking circuit for itself through its lower winding, front contact and armature to the holding ground of conductor 31. On the energization of relay 80, an operating circuit is closed through the right-hand winding of relay 81 for operating it. This closes a temporary holding circuit from ground at the outer front contact and armature of relay 81, conductor 83, armature, front contact and left-hand winding of relay 29, to grounded battery over conductor 34. This circuit insures that the relay 29 will remain energized, until its locking circuit through its right-hand winding is completed. When the numerical key No. 6 is released, relay 80 deenergizes and a locking circuit is closed through the left-hand winding ofrelay 81,

y the right-hand winding of this relay, the relay 81 is again short-circuited and the units register .is in condition to be adjusted in accordance with the units digit of the wanted number which, in this instance, is No. 4. The operator now depresses numerical key N o. 4 and thereby closes a circuit from ground, through the contacts 98, conductor 99, upper armature and front contact of relay 21, sender preselector brush 100, conductor 101, right-hand armature and front contactof relay 28, lower windin of marginal relay 102, conductor 103, wlnding of relay 80, to grounded battery. On the release of the No. 4 numerical key, the stations register switchin relay 27 is energized and locked operated 1n manner similar to the actuation of the other switching relays and the units re ister switchin relay 28 deenergizes and t e relay 81 o Flg. 1 is short-circuited, as previously described. Since the wanted subscriber is party R, the operator presses the party key for this party which, in this instance, is the same as the numerical key for No. 3. On the operation of this key a circuit is closed from ground, resistance, key contacts 104, conductor 76, innermost armature and front contact of relay 21, sender preselector brush 77, conduc tor 93, armature 105 and front contact of switching relay 27, lower windings of sensitive relay 165 and marginal relay 226, through conductor 103 and Winding of relay 80 to grounded battery. r1`he marginal relay 226 does not operate in series with the mentioned resistance, but the sensitive relay 165 attracts its armatures and locks itself operatedthrough its upper winding, front contactand armature to ground, over conductor 31.

1n the event that the wanted number is an individual line without the party letter, the operation of the start key 108 functions the same as operating the key for party J which-key operates relay 106 of the stations register. This will indicate to the B operator that station J is wanted and, when she operates the ringing key for party vJ, 33 cycle ringing current is selected which will signal the individual line. It will thus be seen that,when the kstart key is operated on a call for a party line other than party J, relay 106 will not be operated because of the fact that the operation and release of a key to operate a relay of the stationls register releases the relay 27 so that any subse uent operation of the numerical keys wil not te ect the adjustment of any of the regisers.

After the A operator has adjusted the numerlcal registers in accordance with the designation of the wanted number, the start key 108 is depressed and held until the indicator pilot lamp 109 of Fig. 1 is lighted.

The lighting of the lamp 109 is effected by Y the closure of the circuit including the conductor 111 which is closed at the left-hand armature and front contact of rela 110 Which relay is operated as will now e described.. On the depression of the start key, a circuit is closed from grounded battery, resistance, upper contact of start key 108, winding of relay 18, conductor 112,' outer left-hand armature and front contact of relay 40 (which it will be remembered was energized as soon as the link finder of Fi l .had seized an idle link), left-hand windln of relay 110, through the back contacts an continulty springs of other relays similar to relay 110 of other positions located at link nders operated from the Main office keys. It will thus be seen that if no other operator has a start key similar to 108 depressed on a call to the Main office, relay 110 will opcrate and lock itself operated through its continuity spring, armature and right-hand wmdmg and uppermost armature and front contact of rela 17. Relay 110 on attracting its armatures reaks the series ground circuit which is arranged so that no other operator can disturb the connection under completion until the operator in attendance on the present call has released her start key and then onl one operator can e'ect the operation of t e relay corresponding to 110 at another position. When 110 attracts its armatures .in the manner described, it closes a circuit to light the indicator pilot lamp as previously described which informs the operator that the cord circuit in her position is associated with the common indicator board shown in the upper left-hand corner of Fig. 2. Relay 110 at this time also closes a circuit to o erate relay 113 which circuit is traceable rom grounded battery, winding of this relay, conductor 114, link iinder brush 43, left-hand front contact and armature of relay 110 to ground. Relay 113 is thus operated and closes an actuating circuit for relay 37 extending from grounded battery, -ri ht-hand winding of this relay, innermost ront contact and armature of relay 113, u permost front contact and armature of re ay 47, armaturev and back contact of relay 115, trunk finder brush 52, windin or' sensitive relay 116", winding of margina relay 117, front contact and armature of relay 55 (which was energized in series with relay 47) to ground. The operation of relay 117 is eective to light the tens and units lamps on the indicator board to indicate the trunk designation of the trunk assigned for use, into the jack of which 118 the operator will insert the calling plug 119 of her cord circuit. In the drawlng this trunk is shown as trunk No. 12 and the marginal relay 117 completes circuits to light the tens lamp 120 and the units lamp-121. On receiving this number indication, the operator inserts the calling plug 119 of the cord circuit taken for use into the jack 118 and releases the start key 108 which extinguishes the lamps on the common indicator board as will be pointed out. When the start key 108 is released, at its upper contacts it opens thel circuit which has been locking the relay 17 operated and since the relay 18 is slow to release its armature, the original locking circuit of lrelay 17 is open at the continuity spring and contact of rela 18. Therefore the relay 17 deenergizes an as soon as it retracts its ar- -matures, it opens the locking circuit Jfor relay 110 whic extended through the uppermost front contact and armature of relay 17 and relay 110 on deenergization causes rela 113 to release its armatures. Also at the iower armature and contact 124 of relay 17, the energizing circuit of relay 39 is interrupted and th1s circuit releases its armatures and thereby causes the dee'nergization of relay 47. The operators circuits and the link finder which has just been in use are now in normal condition and in readiness for use on a subsequent call.

When relay 113 of the trunk finder is released, as above described, the low resistance Winding of relay 37 is disconnected from thev windings of the sensitive relay 116 and marginal relay 117 of the trunk circuit. Relay 37 and relay 116, however, do not deenergize because of a circuit extending from grounded battery through both windings in series of relay 37, its inner front contact and armature, armature and back contact of relay 115, trunk nder brush 52, relays 116 and 117, to ground at the front contact and armature of relay 55. Because of the high resistance winding of relay 37 now included in this circuit, the marginal relay 117 deenergizes and extinguishes the lamps on the indicator board whlchhave been lighted for indicatin the trunk assignment. Relay 37 now ho ds the trunk finder busy and also causes the sensitive relay 116 of the trunk and the lrelay 57 of the sender finder to remain operated. Since the calling plug 119 of the A operators cord circuit is in enga ement with the jack contacts 118 of trunk o. 12, the relay shown at the right of Fig. 1 is held operated from grounded battery, through the sleeve contacts of the mentioned plug and jack winding of the relay 55 to ground over conductor 218, at the armature and back contact of a relay similar to 55 at another trunk of this group. Relay 55 while operated, indicates that trunk No. 12 is in use.

When the common set of numerical keys of an operators position such as that shown at the lower left-hand corner o f Fig. 1 is released, it is immediately connected to an idle register sender of the common group of register senders ofy which there are only enough provided to handle simultaneously calls to all offices, during the interval that transp'ires between the depression of the otlice key by the A operator, until the number indication has'been transferred to the \B operators number indicator. It will be recalled that when relay 18 was energized at the close of the operation fof the numerical keys, relay 14 deenergized. rlhis closed an energizing circuit for relay 13 as lon as preselector brush 24 tested test contacts laving a busy potential applied atthe armature and front contacts of relays similar to relay at engaged register senders. With relay 13 operate motor magnet 20 advances the preselector brush to select an idle register sender.

As soon as the number has been set up on the ke set in the manner indicated and when t e start key is operated, the operator receives the trunk assignment by the lighting of trunk indicator lamps, such as 120 and 121 on the common indicator board and thus it is not necessary for this trunk assignment to be transmitted to the A operator from the B operators position over an order wire.

It will be understood that the registers of a register sender remain adjusted to store up the number designation of the wanted number until the B operator is -in readiness to receive this indication on the number indicator shown at the right of Fi 2 and at the lower part of Fig. 3, thus 1t is not necessary for the A operator to repeat the wanted number to the B operator. It will be pointed out in this description how the wanted number is displayed on the indicator at the B position until the B operator is in readiness to attend to the call and it remains as a visual indication of the wanted number until the B operator extinguishes the operated number indicating lamps either by operating a common release key 125 or by insertin the plug 126 into a multiple jack 127 of t e wanted line. A

The B operator receives the indication of the wanted line over selected trunk No. 12 when the A operator depresses the start key 108 of Fig. 1, which operation closes a circuit from ground, winding of relay 129 of Fig. 2, sender brush 130 in its normal position, conductor 131, sender finder brush 60, lowermost front contact and armature of relay 57, conductor 132, trunk inder brush 50, uppermost front contact and armature of the sender switch into its zero position.

vswitch to advance it into position 1.

This circuit is traceable from the armature and front contact of relay 129, sender brush 136, conductor137, back contact, armature and winding of motor magnet 126 of the sender switch, to grounded battery. The operation of relay 135 closes a circuit for operating the slow releasing relay 138 and this relay connects the lamp 139 in circuit with the intermittently closed contacts 140 of the common flashing device, this circuit being traced from grounded battery, through the lamp 139, inner armature and front contact of relay 138, armature and back contact of relay 141, conductor 142, contacts of the flasher 140, to ground. On noting that lamp 139 is intermittently lighted, the operator presses the assignment key 143 and thereby closes a circuit for operating the relay 134 which extends from ground, through the contacts of this key, upper winding of relay 134, conductor 144, receiver brush 145 in its normal position, armature, back contact and winding of the motor magnet 1,46, to grounded battery. This circuit is eHective to cause the energization of the relay 134 which thereupon closes a locking circuit for itself from grounded battery, contacts on the release key 125, conductor 147, winding of relay 148, conductor 149, lower winding, front contact and armature of relay 134, conductor 150, to ground at the inner armature and back contact of relay 151. The guard lamp 152 is energized in multiple with this last described circuit. Relay 148 is operated in the locking circuit just described and closes an operating circuit for the motor magnet 146 of the receiver circuit is traceable from grounded battery, winding of motor magnet 146, its back contact and armature, receiver brush 145 in its normal position, right-hand front contact and armature of relay 148 to ground. As soon as the receiver switch moves out of its normal position, no other relay such as 134 can be operated by falsely pressing another assignment key, because the battery potential through the winding of the motor magnet 146 is removed from these relays when the receiver switch leaves its normal position. The operation of relay 134 also disconnects the tip and ring conductors 133 and 153 from the B operators cord circuit and connects these conductors to the

brushes

154 and 155 of the receiver switch. The opening @of conductor 133 causes relay 135 to deenergize and also effects the denergization of This that this operator can depressthe stations` key while the remainder of the wanted number designation is being received. Since the receiver and sender switches step alternately and since each switch must complete twentyone steps to effect the number designation at the registers of the B operators position, the total number of steps taken by both of these switches 1s forty-two and will require about one second of time to display the'complete deslgnation of the wanted line, after the B operator presses the assignment key 143.

It Will be remembered that the sender and recelver switches are each in position 1 so that a circuit is now extended from ground, winding of relay 160, conductor 161, brush 154, uppermost front contact and armature 0f relay 134, tip conductor 133 of the selected trunk, uppermost armature and front contact of relay 116, tru-nk finder brush 50, conductor 132,- lowermost armature and front contact of relay 57, sender finder brush 60, conductor 131, brush 130 in position 1, conductor 162, upper front contact of relay 106, but, since relay 106 was not opera-ted, this circuit is incomplete at this point. Aft this time a circuit is closed from ground, through the low resistance winding of relay 166, brush 155, inner upper armature and front contact of relay 134, ring conductor 153, of the trunk selected` inner upper armature and front 'Contact of relay 116, trunk finder brush 51, conductor .167, armature and front contact of relay 5T, sender finder brush 59, brush 168 in position 1, through both windings in series of relay 169, to grounded battery. The relay 166 will not operate in series with the high and loW resistance windings of relay 169 but this last mentioned relay will be energized to close a circuit for advancing the. sender switch to position 2. This circuitl may be traced from grounded battery, winding of the motor magnet 126 of the sender switch, armature and back con-tact of this magnet, conductor 137, b-rush 136 in position 1, fron-t contact and arma-ture of relay 169, t0 ground. In position 2 of the sender switch, the low resistance winding of relay 169 alone is connected through brush 168 and sender finder brush 59 to the ring conductor 153 of the selected trunk through brush 155 and low resistance winding of the relay eov 166 to ground. Relay 166 is energized in this circuit and causes the motor magnet 146 of the receiver switch to be advanced in a circuit traceable from grounded battery, winding`v back contact and armature of this magnet. brush 171 in position 1, front contact aud armature of relay 166, to ground. In position 2 of the receiver switch, the relay 192 is connected tothe stations register of the A oilice over a circuit extending from grounded battery, conductor 231. winding of relay 192, conductor 232, receiver brush 154 in its second position, uppermost front Contact and armature of relay 134, tip conductor 133 of the selected trunk, upper armature and front contact of relay 116, trunk finder brush 50` conductor 132, lowermost armature and front contact of relay 57 sender finder brush 60, conductor 131, sender switch brush 130 in its second position, conductor 234, but this circuitv is in complete. at the upper front contact and armature of relay 107 so that relay 192 1s not operated. lVhile the. receiver switch is in position 2, the high resistance winding of relay 166 is connected in series with the low resistance windingof relay 169 at the sender switch, causing this last mentioned relay to deenergize while the relay 166 at the receiver switch remains operated. The sender switch is now advanced to position 3 in a circuit traceable from grounded battery, winding of its motor magnet 126, ar-

f mature and back contact of this magnet,

conductor 137, brush 136, conductor 170, back Contact and armature of relay 169, to ground. In position 3 of the sender switch a circuit is closed from ground through both windings of relay 173, brush 168 of the sender switch, brush 59 of the sender finder switch. middle contact and armature of relay 57 conductor 167, trunk nder brush 51, inner front contact and armature of relay 116 over ring conductor 153 of the trunk, inner armature and front contact of relay 134` receiver switch brush 155 in its second position, through both high and low resistance windings of relay 166, to ground. The relay 166 deenergizes and thereby completes a circuit for the motor magnet 146 to advance the receiver switch into position 3. As soon as the receiver switch enters this position, a circuit is closed for operating relay 193, extending from ground, winding of' this relay. conductor 235, receiver switch brush 154. uppermost front contact and armature of relay 134. tip` conductor 133 of the selected trunk, uppermost, armature and front contact of relay 116, trunk finder brush 50, conductor 132, lowermost armature and front Contact of relay 57, sender finder brush 60, conductor 131, sender switch brush 130, conductor 236, lowermost front contact and armature of relay 165, resistance to grounded battery. The relay 193,

also closed from battery, through the low resistance winding of relay 172, brush 155, over the circu-it previously described to brush 16S of the sender switch in position 3, through the high and low resista-nce windings of relay 173, to ground. Relay 173 is operated in this circuit an-d at its front contact and armature closes an operating circuit for the motor magnet'126which advances the sender switch intol position 4. In this position, the low resistance winding of relay 173 is connected to trunk conductor 153 to energize relay 172, which closes an operating circuit for magnet 146 of the receiver switch for advancing this switch into position 4. The high resistance winding of relay 172 is now included in the circuit eX- tending over` trunk conductor 153, and through the low resist-ance winding 0f relay 173 which causes this last named relay to deenergize and advance the sender switch into position 5, where battery potential is extended through both windings of relay 169, brush 168, sender finder brush 59, front contact and armature 0f relay 57, conductor 167 trunk finder brush 51, front. contact and armature of relay 116, conductor 153, inner armature and front contact of relay 134, lbrush 155, through both windings of relay 172, t0 battery potential. This causes relay 172 to deenergize and advance the receiver switch into position 5. This alternate operation of the sender and receiver switches continues, until both-switches are advanced to position 21.

It will be seen that the brush 154 of the receiver connects the twenty relays of the indicator successively to the tip conductor 133 of the selected trunk as the receiver switch advances its brushes through position 1 to 20, inclusive. The brush 130 of the sender switch connects the mentioned tip conductor 133 of the selected trunk vsuccessively to corresponding relays of the registers and the register relays which have been operated in response to the depression of the numerical keys will close circuits to operate and lock corresponding relays at the indicator at the wanted ofiice. It should be noted that the relays of the register sender and of the indicating device are so connected to the various contacts of the sender switch and receiver switch, that as these switches are advanced, current is reversed in the signaling circuit in each succeeding positions of these switches. In this way the overlap, when the sender switch moves, will not falsely operate a relay at the wanted office.

In the case assumed, relays A, B, E, F, I,

` K, N and G of the sender registers were locked operated in res onse to the depression of the proper keys o the numerical key set and, after the operation of the sender and receiver switches has taken place, corresponding relays will be ener 'zed and locked operated in the receiver of t e dlstant oilice. With these last mentioned relays operated, circuits can readily be traced for ighting only the stations lamp R, thousands lamp No. 7, hundreds lamp N o. 7, tens lamp No. 6 andl units lamp No. 4.

When the sender switch reaches osition 21, a circuit is closed from groun ed battery, winding of magnet 126, conductor 137, brush 136, conductor 180, sender finder 'brush 58, upper armature and front contact of relay 57, winding of relay 115 to ground. The magnet 126 remains inert, but the rela 115 is operated to open the operating circult of the relay 116 of the trunk and the o erating circuit of relay 37 of the trunkv der. Relay 37 in turn opens the holding circuit of relay 57 of the sender finder swltch and the relay 65 of the sender which rela in turn causes relay 25 to deenergize. en relay 25 retracts its armature, it closes a circuit from ground, through the sender switch brush 128, conductor 127, back contact, armature and winding of motor magnet 126 to grounded battery and thereby advances the sender switch into its normal position, while the relay 25 at its front contact o ens the locking circuit which has been vhol ing the actuated relays of the registers in operated position. The trunk finder and the sender finder remain in the position last used.

After the lighting of the indicator lamps at the distant oiiice, the B operator notes the designation of the wanted l1ne and tests the multiple of the wanted line in the well known manner and, if this line is idle, inserts the plug 126 into the multiple jack 127 of this line. This last operation actuates the sleeve relay 151 which thereupon opens the conductor 150 by which the relay 134 and relay 148 have been held operated. Relay 134 deenergizes and extends the conductors 133 and 153 of the selected trunk through the windings of the repeating coil of the B operators cord circuit. The relay 148 upon deenergizing closes a circuit from ground, through its armature and back contact, brush 145 of the receiver switch, armature, back contact and winding of the motor magnet 146 to grounded battery which circuit is effective to advance the receiver switch to its normal position.

The B operator, after inserting the plu 126 into the multiple jack 127 of the wante line, depresses the party key 190 for connecting ringing current of the proper frequency to signal the wanted subscribers station. The depression of key 190 also closes contacts 241 which close a circuit for the erated in multiple-with the last described circuit through its continuity spring and 'contact and, when operated, closes a locking circuitfor itself through its continuityv spring and armature. As soon as the rela 242 is operated, it closes a ringing circuit from the source of current through the de pressed party key 190 and in series lthrough the back contacts of

keys

189 and 188, con# ductor 243, lower front contact and armature of relay 138, winding of trip relay 244, upper front contact and armature of ringing relay 242 through the lower side of the operators cord circuit and called line in series, through the tuned ringer at the B subscribers station over the upper side of this line and the operators cord circuit in series to ground at the uppermost armature and front contacts of ringing relay 242. When the called party responds, the trip relay 244 attracts its armature to short-circuit the ringing relay 242 which thereupon opens its locking circuit and remains inert to pre.- vent inadvertent reapplication of signalling current on this connection. Also, when the ringing relay 242 retracts its armatures, it completes a circuit for the supervisory relay 245 through which talking battery 1s supplied to the wanted subscriber. The supervisory relay is maintained operated in this circuit and closes a circuit to apply talking battery to the answering end of the B operators cord circuit through lthe winding of relay 135 and impedance coil 246.

It has not been deemed necessary to fully disclose the details of the operators cord circuits by which supervision is obtained since these operations take place in the same manner. as in multi-oiiice telephone sys-` tems now in use. It will be sufficient to understand that at the termination of the conversation, proper signals will be displayed to the A and B operators who thereupon manually restore the cord circuits which have been in use.

It should be pointed out that the B operator can increase the speed of completing connect-ions at her position by operating the common release key 125, as soon as she has noted the designation of the wanted line instead of waiting for the release operation of the receiver relay registers to be effected by inserting the plug 126 into the multiple jack 127.

By arranging the incoming trunk circuit with a so-called automatic busy test arrangement, that is, an arrangement wherein the operator does not have to test the mul tiple of a wanted line but simply lnserts. the plug of lier cord circuit into a multiple Jack of this line whereupon autom'atlc means completes the connection, if the wanted line is idle, and prevents the completion of this connection, if the wanted line is engaged, the B operator need not be provided' with a telephone set. While in this disclosure manual party keys have been disclosed for selecting the current of proper frequency for selecting. wanted stations on a party line, it will be understood that the system herein disclosed will be equally effective, if the signalling current is selected automatically.

What is claimed is:

l. In a telephone system, an operators position, telephone lines terminating in said position, a second operators position, other lines terminating thereat, trunk circuits connecting said positions, a trunk indicating device at said first position, a line indicating device at said second position, means at said first position whereby an operator receives the designation of wanted lines, means controlled at said position for initiating a connection to a wanted telephone line, means responsive thereto for selecting.

an idle trunk to said second operators position and for causing said trunk indicating device to give the trunk indication of the selected trunk line at said first operators position, a circuit for connecting the calling line and the selected trunk, means controlled at said iirst position for causing said line indicating device to give the designation of the wanted line, and a manual switch by means of which an operator at said second position connects the selected trunk to the wanted telephone line.

2. In a telephone system, a plurality of operators positions, each provided with a numerical key set, a plurality of senders common to said positions, means for allotting senders for use, means controlled at an operators position for associating its numerical key set with an allotted sender whereby said sender is variably adjusted in accordance with a predetermined code, other operators positions each provided with an indicating device, and means under the control of a sender for operating an indicating device in accordance with the adjustment of said sender.

3. In a telephone s stem, a plurality of oiiices, la plurality o trunk circuits connecting one oice with a second oiiice, a plurality of senders at said first oHice, means for preselecting a sender for use ahead of the call, a plurality of switches, a link circuit terminating at one end in a switch for selecting a trunk circuit and terminating at its other end in a switch for seizing a preselected sender, a third switch for seizing an idlelink circuit, means for variably `adjusting a selected sender, and means for transmitting impulses through said first and second mentioned switches to the selected trunk.

4. In a telephone offices, trunk circuits connecting one oice with a second olice, a plurality of Senders, means for preselecting a sender Jfor use ahead of the call, a plurality of switches, means for variably adjusting a preselected sender in accordance with a predetermined code, a link circuit terminating at one end in a switch operating to seize a trunk circuit, said link circuit terminating at its other end in a switch for seizing a preselected sender, a third switch for seizing an idle link circuit and thereby eiect the operation of said irst andsecond switches, an indicating device at the second oiiice, and means controlled by said adjusted sender and controlled through said first and second switches over a selected trunk for selectively operating said indicating device.

v5. The methodof completing a telephone connection which consists in the subscriber repeating the number of the wanted line to system, a plurality of an operator, said operator thereupon man- Aually selecting the oiiice through which a wanted subscriber can be reached, selecting a trunk to said oiiice, visually signallingthe designation of the selected trunk to said o erator, said operator then connect-ing tiie calling subscriber and the selected trunk, visually signalling the number of the wanted subscriber to a second operator, and connecting the wanted line to the designated trunk.

6. In a telephone system, a plurality of oiiices, an A operators position at one of said oiiices, B operators positions at the other oiiices, trunks for connecting said A operators position to each of said other ofices, oiiice keys one for each oilice accessible to said A operators position, and means responsive to the operation of 'an oiice key for automatically selecting a trunk to a wanted oiiice and for automatically indicating the designation of said trunk to said A operators position.

7. In a telephone system, a plurality of telephone oilices, an A operators position at one of said offices` B operators positions at the other oiiices, trunks for connecting said A operators position `to said other oiices, office keys one for each oice accessible to said A operators position, automatic switchmg means operating responsive to the operation of one of said keys for automatically selecting trunks to a wanted oilice, and automatic indicating means for giving the designation of selected trunks.

8. In a telephone system, a plurality of telephone oliices, a plurality of A operators positions at one of saido ces, B operators positions at each of said other offices, trunks leading from said A operators positions to each of said other ofiices, an oflice key at each A operators osition for each oilice reached from said A.) o erators positions, .a trunk indicator at said A operators positions, a number indicator at each of said distant oices, a plurality of senders common to said operators positions and variably adjusted therefrom, and means responsive to the adjustment of said senders for selectively operating said number indicators.

9. In a telephone system, a number storing device comprising groups of marginal and sensitive relays, each group of relays serving to store the designation of one digit, a single set of ten numerical keys and means for successively and variably adjustin said groups of relays under the control o said set of keys.

10. In a telephone system, operators positions each of which is provided with a single set of ten numerical keys, a plurality of sets of number storing devices common to said operators ositions, means for associating an idle set ci) number storing devices with the key set of an operators position, means for successively operating said set of keys for variably adjusting the associated set of number storing devices, and means selectively actuated by said set of number-storing devices.

11. In a telephone system, a plurality of operators positions each of which is provided with a single set of ten numerical keys, a plurality of register senders common to said operators positions, each register sender comprising a plurality of groups of relays, means for associating an idle register sender with the key set of an operators position, and switching means for each register whereby the repeated operation of a key set is effective to operate a diii'erent group of relays of the associated sender.

12. In a telephone system, a plurality of operators positions each of which is provided with a single set of ten numerical keys, a plurality of register senders common to said operators positions each register sender comprising a plurality of groups of relays of various degrees of electromagnetic sensitivity, means for associating an idle register sender with the key set of an operators position, and' switching means for each register whereby the repeated operation of a key set is effective to operate a different group of relays of the associated sender.

a plurality of 13. In a telephone system, two telephone ofiices, an A o erators position atA one of said offices, a operators position at the other oiiice, a register sender at the A operators position comprising a group of registers arranged to be selective y operated under the .control of the A operator, a progressively movable switch associated with said register sender, an indicating device at the B operators position, a progressively movable switch associated therewith, and means for operating said switches alternately whereby the registration on said revister sender is transferred'to the indicating device at the B operatorsposition.

14. In a telephone system, an A operators position, a register sender including a progressively movable switch' located at said position, means at said position for variably adjusting said register sender in accordance with a predetermined code, a B operators position, a trunk circuit connecting said operators positions, an indicator at said B operators position arranged to be variably operated in accordance with the settingof said register sender,a progressively movable' switch associated with said indicator, means for settin said switches in operation, means effective t ereafter whereby the switch associated with said indicator completes operating circuits for the switch associated with said' register sender and means whereby the switch associated with the register sender closes operating circuits for the switch associated with said indicator, and means functioning during the advance of said switches for effecting the operation of the indicator in accordance with the adjustment of said register sender.

l5. In a telephone system, a plurality of offices, a plurality of A operators positions at one of said oilices, a B operators position at the other oilice, a plurality of register senders for the use of said A operators positions arranged to be variably adjusted therefrom, means for associating an idle register sender with an A operators position, each of said register senders bein provided with a progressively movable sen er switch, a trunk circuit connecting said A operators positions and said B operators position, an indicating device located at said B operators position and a progressively movable receiver switch associated therewith, means for initiating the operation of said switches, other means eilective thereafter whereby the receiver switch effects the advance of the sender switch, additional means whereby the sender switch effects the advance of said receiver switch, and means operating under the control of said switches whereby the register sender effects the operation of said indicator over said trunk circuit.

16. In a telephone system, a plurality of oiiices, a plurality of A operators positions at one of said offices., a B operators position at the other oiiice, a single strip of keys at each A operators posit1on, a plurality of register senders for the use of said A operators positions and arranged to be variably adjusted by said keys, means for associating an idle register sender with an A operators position, each of said register senders being provided with a progressively movable sender switch, a trunk circuit connecting said A operators positionsand said B operators position, an indicating device located at said B operators position, a'progressively movable receiver switch associated therewith, means for initiating the operation .otiices, a plurality of A operators positionsA at one of said offices, a B operators position at the other oiiice, a plurality of register senders for the use of said A operators positions arranged to be variably adjusted therefrom, means associated withd each A operators position for preselecting an idle register sender, each of said register senders being provided with a progressively movable sender switch, a trunkv circuit connecting said A operators positions and Asaid B operators position, an indicating device located at said B operators position and a progressively movable receiver switch associated therewith, means for initiating the operation of said switches, other means eective thereafter whereby the receiver switch ei'lects the advance of the sender switch, additional means whereby the sender switch effects the advance of said receiver switch, and means operating under the control of said switches whereby the register sender effects the operation of said indicator over said trunk circuit.

18. In a telephone system, a plurality of oiiices, a plurality of A operators positions at one of said offices, a B operators position at the other oiiice, a plurality of register senders for the use of said A operators positions, each of said register senders including a plurality of relays arranged to be variably adjusted from said operators positions, means for associating an idle register sender with an A operators position, each of said register senders being vprovided with a progressively movable sender switch, a trunk circuit connecting said A operators positions and said B operators position, an indicating device located at said B operators position and a `progressively movable receiver switch associated therewith, means for initiating the operation of said switches, other means effective thereafter whereby the receiver switch effects the advance of the sender switch, additional means whereby the sender switch effects the advance of said receiver switch, and means operating under the control of said switches whereby the register sender effects the operation of said indicator over said trunk circuit.

19h. In a telephone system, a plurality of operators positions, each of said positions being provided with a single set of keys, a plurality of number storing devices for the common use or' saidpositions and arranged to be variably adjusted in accordance with the operation of said key set, and a progressively movable preselector switch for each operators position for associating the key set of that position with an idle register \sende r.

20. In a telephone system, a plurality of operators positions, each of said positions being provided with a single strip of keys, a plurality of senders common to said operators positions, each sender having a plurality of registers arranged to be'successively operated by the repeated actuation of a strip of keys.

21. In a telephone system, an A operators position, a B operators position, telephone lines terminating at each of said positions, a trunk circuit extending between said posi tions, a register sender in said A operators position arranged to be variably actuated 1n accordance with the designation of a wanted telephone line, an indicating device at said B operators position, and means having a signaling circuit including at least one of the conductors of said trunk circuit for transferring the designation recorded -on said register sender to said indicating device,

said means including mechanism for reversing the direction of current flow in said signaling circuit a plurality of timesduring the transfer of the designation from said register sender to said indicating device.

22. In a telephone system, an A operators position, a B operators position, telephone lines terminating in said positions, a trunk circuit extending between said positions, a register sender at said A operators position arranged to be actuated in accordance with the designation of a wanted telephone line, an indicating device at said B operators position, a signaling circuit including at least one conductor of said trunk circuit for transerring the designation -of said register sender to said indicating device, meansat said B operators position for connecting said trunk circuit to the indicated line, and two means for releasing said register sender and said receiving device prior to the termination of the connection.

22. In a telephone system, an A operators osition, a B. operators position,l telephone ines terminating at each of said positions,

a registering device located at said A operators position and arranged to be actuated in accordance with the designation of a wanted telephone line, an indicating device located at said B operators position, a signaling circuit including at least one conductor of said trunk circuit for transferring the designation of said wanted telephone line from said registering device to said indicating device, a release key, and switching means for connecting said trunk circuit to said wanted telephone line, said release and indicating devices.

In witness whereof, I hereunto subscribe my name this 2nd day of December A. D.

WINFRED T. POWELL.