US1573991A

US1573991A - Signaling system

Info

Publication number: US1573991A
Application number: US756396A
Authority: US
Inventors: Paul B Murphy
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1924-12-17
Filing date: 1924-12-17
Publication date: 1926-02-23
Anticipated expiration: 1943-02-23
Also published as: DE602988C

Description

Feb. 23 1926. 1,573,991

P. B. MURPHY SIGNALING SYSTEM Filed Dec. 17, 1924 4 Sheets-Sheet 1 0per's.TeL

Feb. 23 1926.

P. B. MURPHY SIGNALING SYSTEM 192-; 4 Sheets Sheet 2 Filed Dec. 17

Feb. 23 1926. I 1,573,991

P. B. MURPHY SIGNALING SYSTEM Filed Dec. 17, 1924 4 Sheets-Sheet 3 40/15. Max my e 1 w Feb. 23 1926.

P. B. MURPHY SIGNALING SYSTEM 4 Sheets-Sheet 4' Filed Dec. 17, 1924 Mum/0r: aw 23 Mar "My J77]:

Patented Feb. 23, 1926.

UNITED STATES PATENT OFFICE.

PAUL B. MURPHY, F NYACK,

NEW YORK, ASSIGNOB TO WESTERN ELECTRIC C OH- PANY, INCORPORATED, OF NEW YORK, N. Y., A CQRPORATION OF NEW YORK.

srenanme srsrnn.

Application filed December To all whom it may corwern:

Be it known that I, PAUL B. Mom-Hr, a citizen of the United States of America, r siding at Nyack, in the'county of Rockland and State of New York, have invented certain new and useful Im rovements in Signaling Systems, of whic the following is a full, clear, concise, and exact description.

This invention relates to signaling systems and more particularly to improved methods and meansfor signaling over transmission lines. a

Under the present telephone practice involving the use of telephonelines inter-connecting different exchanges, several different methods of extending connections are employed, such as manual to manual, manual to automatic or automatic to automatic connections. In a manual to manual connection, the subscriber in the originating exchange first secures a connection to atoll operators position in his own exchange, who

' then extends the connection over a toll line to a distant exchange and rings up the toll operator at such an exchange. The toll operator at this exchange requests of the originating toll operator, the number of the desired line and then proceeds to extend the connection to the desired subscriber. .In'a manual to automatic connection the toll operator in the originating exchange dials the desired line in the automatic exchange without the aid of the toll operator at a distant exchange and in an automatic to automatic connection, no operators are involved but the calling subscriber merely dials thefnums ber of the Wanted subscriber and the connection is completed over the toll line between the two exchanges. Connections of these types may extend througha number of manual or automatic exchanges involving the use of several toll lines.

It is the object of this invention to provide cord circuit and toll line equipments suitable for use in the extension of connections of the above types.

Another object is to provide means associated with such cord circuits and toll line equipments, whereby any one of the well known types of toll lines may be employed such as, for example, ordinary wire toll lines with or without repeaters, a channel of a carrier telephone installation, a radio telephone connection, composite lines or phan- 17, 1824. Serial No. 758,396.-

tom lines. That is, the nature of the signals used for performing the various functlOIlS incidental to the extension of a connection is such that the signals may be transmitted over any toll line the same distance and at the same efiiciency as the ordinary voice modulated signals and without in any way curtailing the usefulness of these various types of toll lines.

To attain these objects according to One feature of the invention sources of alternatmg current of a common frequency within the voice frequency range are employed for the signals transmitted over the toll lines to accomplish the various switching and supervisory functions, that is, a single frequency is used for'the signals transmitted in both directions over a line, and means is provided at each end of the toll line for composing distinctive signals by interruptions of this common frequency at various rates and for transmitting such signals to the receiving end to cause corresponding,switching and signaling functions to be peiformcd.

Anotherfeature is the provision of means, .including the use of currents ofthe- 'com'mon '-frequency,-- whereby if a supervisory signal is being transmitted in one direction over a l1l1e, a supervisory signal transmitted in the opposite direction over the line is not inter- .fered with, but on the other hand, causes the first signal to be temporarily or permanently suspended as desired while the second signal performs its assigned function. This means is particularly applied in this system to the reringing of a called subscriber when a supervisory signal is being transmitted to v the calling subscriber as an indication that the called subscriber has hung up his receiver. In this case the supervisory signaling is resumed after the reringing signal ceases and continued until the called subscribcr answers a second time.

Another feature is the provision of means, also including the use of currents of the common frequency, whereby a disconnect signal may be transmitted at any time from the originating end of the line during the establishment of a connection or after a connection has been established, regardless of the type of signals that may happen to be transmitted in the opposite direction over all trunks busy signals, or called subscribveniently and cheaply maintained and con-' trolled.

The nature of the invention will more fully appear from the'following specification read in connection with the accompanying drawings in which Fig. 1 shows the connection from a subscribers line diagrammatically with a toll opcrators cord circuit and associated dialing circuit arranged in accordance with this invention located at one manual exchange. By means of this equipment a toll operator may extend connections either to another toll operator located at another manual exchange or to a subscriber reached through an automatic or machine switching exchange. Fig. 2 represents the outgoing end of a special toll line equipment arranged in accordance with the invention, located at the originating exchange, and by means of which voice frequency alternating current signals may be transmitted to and-received from the distant exchange over any type of toll line associated therewith. Fig. 3 represents the incoming end of the special toll line equipment arranged in accordance with this invention, located at a distant exchange, and by means of which voice frequency alternating current s gnals may be received from or transmitted to the originating exchange. Fig. 4 represents a portion of an automatic exchange by means of which automatically called subscribers lines may be reached from the above mentioned toll line equipments.

Referring now to the drawings, trafiic over the system shown and arranged in accordance withthis invention, may be outlined as follows: If it is assumed that a subscriber at 10 has established a connection as far as to the toll .operators position 100 and the toll operator has inserted the answering plug 12 of the cord circuit shown at 100 into jack 11, and ascertained the number of the desired line, the toll operator will then insert the calling plug 15 of this cord circuit into the jack 210 of the outgoing trunk line equipment 200 associated with the toll line 220 leading to the incoming toll line equipment 300 at a distant exchange. The toll operator at 100 then proceeds in either-one of two manners to extend the connection:

If the wanted subscribers number can only be reached through the servlce of .a toll operator such as the one at position 310 at the distant exchange, she proceeds to call this toll operator in the usual manner well known in the art except that alternating currents within the voice range interrupted at a certain rate is used for the necessary signal indications. That is, she causes instrumentalites in the cord circuit and the outgoing toll line equipment 200 to be operated to transmit voice frequency alternat-' also serve as supervisory signals during the establishment and disestablishment of such a connection as well as when the connection is established.

Similar operations of the system take place if the toll operator at position 310 des res to call the toll operator at position 100. That is, voice frequency alternating currents of 1000 cycles interrupted at a 20 cycle rate are transmitted over the toll line 220 and translated by the receiving circuit equipment 250 at the outgoing toll line equipment 200 into signal indications for the attention of the toll operator at position 100.

On the other hand, if the wanted subscribers line is-located in an automatic exchange such as the one diagrammatically disclosed in Fig. 4, the toll operator at position 100 proceeds by the operation of a dialing key to connect the common dialing circuit equ'pment 150 to the cord circuit shown. By means of instrumentalities associated with this dialing circuit, the cord circuit and the outgoing toll line equipment 200 now cause voice frequency alternating currents of 1000 cycles interrupted at different rates to be transm'tted over the toll line.

In one instance these currents .are interrupted at a 40 cycle rate while in another instance, that is, when the dial is operated, they are interrupted at the rate of dialing. The correspondingly produced signals, when received at the incoming toll line equipment 300, prepare this equipment for the extens'on of an automatic connection and are also translated by the receiving circuit 350 to cause the automatic exchange equipment shown in Fig. 4 to extend the connection to the wanted subscribers line as well as to cause the various supervisory signaling indications to be given during the establishment and disestablishment of the connection.

The arrangement of the toll line equipments are such that various signals for the supervision of the connection are transmitted back; to the toll operator at position 100 during the progress of the call as well as in the breaking down of the connection. Such signals consist of voice frequency alternat; ing currents of 1000 cycles interrupted at various rates such as at a cycle rate or signal indications consisting of the voice fre-.

quency alternating currents of 1000 cycles interrupted at the 40 cycle rate in the shape of impulses of per minute, which latter impulses are used when all of the trunks within the automatic office are busy or signal indications of the voice frequency alternating currents of 1000 cycles interrupted at the 40 cycle rate in the shape of impulses of 120 per minute which impulses are used when the called line is busy. Such signals are all translatedby the receiving circuit equipment 250 at the outgoing toll line equipment 200 into the proper supervisory signal indications for the operator at the position 100.

It is to be understood that the frequency of the alternative current sources mentioned and the rat-es at which the currents are interrupted are simplyillustrative and that the invention is not limited to the employment of these particular values but that any frequency within the voice range and any rates of interruptions most suitable to particular cases in the practice of the invention may be selected.

It is believed that the arrangement shown will be more fully understood from the following detailed description of series of calls of the types that may be completed thereby. The first type of connections to be considered will he calls extended on the so-called ring down basis, i. e., from a subscriber 10 through a toll operators position 100 at the originating exchange to the toll operator attending position 310, at the distant exchange and vice versa. The circuits beyond the position 310 have not been shown as the form no part of this invention and as it 15 well known and understood in the art how manual connections are attended to by outgoing has well as incoming toll operators no further explanations will be made in this respect.

Assuming then that the toll operator at 100 has inserted plug 12 into jack 11 and the operator has ascertained the number of the wanted subscribers line by the connection of-his telephone set to the cord circuit the operation of listening key 32, she proceeds by inserting plug 15 into jack 210 and as a result of this action,

relays

24, 23 and 202 are operated as follows: battery, winding of relay 24, winding of relay 23, left hand makebefore-break contacts of relay 36, sleeve con tac'ts of plug 15 and jack 210, left hand winding of relay 202 outer left hand armature and back contact of relay 216 to ground. The operation of relay 24 performs no useful function at this time. The operation of relay 23, however, closes a circuit for relay 26 as follows: battery, armature and front contact of relay 23, outer right hand armature and back contact of relay 42, winding of relay 26, armature and back contact of relay 30 to ground. It should be noted that a circuit is also closed from the battery at relay 23 through lamp 25 and winding of rela 27 in parallel through armature and back contact of relay 26 to a ground at a normal contact of the listening key 32. However, this circuit is prevented from lighting the lamp 25 and operating the relay 27 as relay 27 is slow to operate in com arison with relay 26, so that this circuit is a most immediately broken. The operation of relay 202 closes an energizing circuit for relay .203 from battery, winding of relay 203, inner right hand armature and front contact of relay 202 to ground. Relay 203 in operating closes a circuit for the busy signal 205 as follows: battery and left hand armature and front contact of relay 203, winding of busy signal 205 to ground operating this signal to indicate to other toll operators that the toll line 220 connected to this equipment is busy. The operator at 1.00 now proceeds to ring the toll operator at the distant exchange by operating ringing key 34. This causes a 20 cycle alternating current source to be connected to the ring lead and ground to the tip lead of the cord circuit and the outgoing toll line equipment in which a bridged circuit containing a condenser 207 and an alternating current relay 208 are located. Relay 208 responds to the 20 cycle current and in operating closes a circuit as follows: battery, winding of relay 209, right hand armature and back contact of relay 217. left hand armature and front contact of relay 208 to ground. Relay 209 operates and disconneets the outgoing end oft-he line from the tip and ring leads to the jack 210 andco'nnects the outgoing end'to a source of 1,000 cycles alternating current, interrupted at a 20 cycle rate. This interrupted 1,000 cycle current is transmitted over toll line 220 and received at the incoming end by the receiving circuit equipment 350 and is there transmitted through the input transformer 352 to the input circuit of vacuum tube 353 where it is amplified. An anti-resonant circuit 354 connected between the plate circuit of the tube 353 and the grid or input circuit of the vacuum tube 355 makes this latter tube responsive to alternating currents which do not vary greatly from 1,000 cycles. Vacuum tube 355 acts as a rectifier for this 1000 cycle current and thereby causes direct current impulses, supplied from the usual B battery at 1000 per second occurrence, to flow in the output circuit, in accordance with the principles governing the functions of rectifiers, as is well-known inthe art. Relay 356, which is polarized or biased to normally hold its armature as shown in the drawing is included in this output circuit. This relay will now therefore respond'to the direct current impulses and operate its armature in the opposite direction from that shown in the drawing and stay operated as long as the impulses are transmitted through the output circuit. T 0 make certain that the relay does not chatter or release between the impulses, it is common practice to insert a condenser as shown in the drawing across the terminals of the relay to create as is well-known in the" art a practically constant direct current through the windings of the relay. \Vhen now therefore the 1000 cycle current received at the p receiving circuit 350 is interrupted, it folvisory lamp 306 to ground causing this lows that the flow of direct current through the output circuit of the rectifier is correspondingly interrupted and consequently the relay 356 is alternately operated and released at the same rate of interruption. That is, the armature of this relay will vibrate in this instance at the 20 cycle rate. telay 357 which is included in the circuit controlled by the armature and contacts of relay 356 and which is tuned to respond to alternating current impulses of the 20 cycle frequency only will therefore operate and stay operated as long as the signal incoming to the receiving circuit 350 remains applied. The operation of relay 357 closes an obvious short-circuit at its armature and front contact to ground at right hand armature and back contact of relay 362 for the energizing circuit for relay 358, causing relay 358 to release. The release of relay 358 closes the circuit for relay 302 as follows: battery, left hand winding of relay 302, inner left hand armature and back contact of relay 303, inner left hand armature and back contact of relay 323, make-before-break contact of relay 358 to ground. Relay 302 operates in this circuit and closes a locking circuit for itself from battery, left hand make-beforebreak contacts'of relay 303, right handarmature and front contact of relay 302, right hand winding of relay 302 to ground and also closes a circuit for busy signals 304 and 305 as follows: battery, left hand armature and front contact of relay 302, windings of busy signals 304.. and 305 in parallel to ground. A circuit is also closed by relay 3.02 from battery, left hand make-before-break contacts of relay 303, right hand armature and front contact of relay 302 through superlamp to light to indicate to the operator at 310 that a connection is desired.

In answer to this signal, the operator at 310 inserts plug 311 into jack 314 and relay 303 is operated over an obvious circuit. The

operation of this relay opens at its makekey connecting her telephone set in the usual manner to the cord circuit and receives the details of the call from the operator at 100 who has also by this time actuated her listening key 32 and connected her telephone set to her cord circuit. The operator at 310 then proceeds to extend the connection to the wanted subscribers line and call the subscriber in accordance with the well established practice in the art of telephony. Conversation between the subscriber at 10 and the called subscriber may then take place.

In case the call extended to the operator at 310 is intended for a subscriber that may be reached through the assistance of an operator at another distant exchange, i. e., if the operator at 310 is merely employed as a connecting operator for a so-called through connection, it may be necessary to send supervisory signals from the operator at 100 at the originating exchange over the toll lines 220 through the incoming toll line equipment 300 to a cord circuit of the operator at 310 and this may be done by the operation of the ringing key 34 whenever such supervisory signaling is desired. The function of the circuits in this instance is the same as that already described when the key 34 was operated the first time except that when relay 358 is released as a result of the reception of an impulse of 1,000 cycle alternating current interrupted at a 20 cycle rate, the relay 340 is operated in place of relay 302 over a circuit as follows: battery, winding of relay 340, inner left hand armature and front contact of relay 303, inner left hand armature and back contact of relay 323 to ground at the make-before-brcak contacts of relay 358. This causes the operation of relay 3&0 which disconnects the tip and ring leadsof the toll line 220 and connects the 20 cycle alternating current source and ground to the tip and ring leads of the switchboard end of the outgoing tollline equipment 300, to the jack 314. to a cord circuit of the operator at 310 causing supervisory indications to be displayed in said cord circuit at 310 as is well known in the art.

In case the incoming operator at 310 at the distant exchange decides to extend a connection to a subscriber that may be attended to-by the outgoing operator at 100, i. e., a connection inthe opposite direction on the toll line 220, a procedure similar to -that (ill described above is followed. The operator at 310 actuatcs her ringing key (not shown) in the same manner as the operator at 100 operated her ringing

key

34, and 20 cycle alternating current and ground are there by connected to the tip and ring leads of the incoming toll line equipment 300 causing the relay 315 bridged across line to operate through the retardation coils 316 and con denser 317. The operatlon of relay 315 closes an obvious operating circuit for relay 320 and this relay, after having disconnected the portions of the tip and ring leads connected to the jack 314, connects current from the 1,000 cycle alternating current source mterrupted at a 20 cycle rate to the tip and ring leads of the toll line 220. This impulse of interrupted voice frequency current 1s transmitted at the outgoing toll l1ne equipment 200 through the upper and inner lower armatures and back contacts of relay 222 and upper lower armatures and middleback contacts of relay 209 to the receiving circuit 250, through the input transformer 252 to the input circuit of the vacuum tube 253 where it is amplified. The anti-resonant circuit connected between the plate circuit of this tube and the grid circuit of a second tube 255 responds to alternating currents which do not vary greatly from 1,000 cycles. The second tube 255 receives the 1,000 cycle current, acts as a rectifier and causes the relay 256 connected in its plate circult to operate and release at a .rate which corresponds to the rate of interruptions of the 1,000 cycles received in the same manner as was explained in connection with the operation and release of relay 356 in the receiving circuit 350, i. e., in this instance the relay 256 will operate and release at a 20 cycle rate. Relay 257 I which is tuned to respond only to 20 cycle current is included-in a circuit controlled by the armature of relay 256 and is consequently operated. The operation of relay 257 causes an obvious shortcircuit to be established for the energizing circuit of relay 258 which is thereby released. The release of this relay closes a circuit for relay 240 as follows: battery, right-hand winding of relay 24:0, left-hand armature and back contact of relay 202 to ground at the normal make before-break contacts of relay 258. Relay 240, in operating, closes a locking circuit for itself from battery, left-hand armature and back contact of relay 203, left-hand armature and front contact of relay 240 to ground through the left-hand. winding of this relay. The operation of relay 240 closes an obvious circuit for the busy signal 205 and also causes the illumination of lamp 241 from the battery at relay 203 through the left-hand armature and front contact of relay 240. v

In answering this signal, the operator at 100 inserts plug 15 into jack 210 and relays phone set in the usual manner to the cord circuit and receives the details of the call from the operator at 310 who has also by this time actuated her listening key corres onding to-key 32 and connected her telep one set to her cord circuit. The operator at 100 then proceeds to extend the connection to the wanted subscribers line and calls the-subscriber. in accordance with the well established practice in the art of telephony. Conversation between the subscriber at the distant exchan e and the subscriber at 10 may now take p ace.

Incase the call extended to the operator at 100 is intended for a subscriber that may be reached through the assistance of an operator at another exchange in this direction, 1. e., if the operator at 100 is merely employed as a connecting operator for a through-connection, it may be necessary to send supervisory signals from the operator at 310 at the distant exchange over the toll line 220 through the outgoing toll line equipment 200 to the cord circuit of the operator at 100. This may be done by the operator at 310 actuating her ringing kev whenever such supervisory signaling is desired. The function of the circuits in this instance is the same as that already described when this ringing key was first operated except that when relay 258 is released as a result of the 1 reception of -impulses of 1,000 cycle alternatmg current interrupted at a 20 cycle rate, the relay 213 is operated in place of relay 240 over a circuit as follows: battery, winding of relay 213, left-hand armature and front contact of relay 202 to ground at the make-before-break contacts of relay 258. This causes the operation of relay 213 which disconnects the tip of ring leads of the toll line 220 and connects the 20 cycle alternating current source and ground to the tip and ring contacts of the jack 210 and plug 15 to the cord circuit of the operator at 100 causing supervisory indications to be displayed thereat as is well known in the art, i. e., relay 30 is operated causing relay 26 to release and lamp 25 to light.

These various connections may be released when the conversations cease by merely removing the plugs and the various relays will consequently return to normal ositions as is well known in the manual telep one art.

The second type of connections to be conpart of this invention, only a small portion automatic equipment may be used as long v has been shown to sufficiently illustrate how it is affected by and how it reacts upon the toll line equipments in accordancewith this invention. In fact any well known type of as the proper signal indications may be sent or received to perform the proper functlons in response to dialing and supervisory signal indications through the toll line equipments.

Let it now be assumed, as hereinbefore described in connection with calls extended on the ring-down basis, that the toll operator at 100 has inserted the plug 15 into the jack 210 and

relays

202 and 203, signal 205, relays 23, 24 and 26 have all been operated and that supervisory lamp 25 is. not light-ed due to the combination of the slow releasing and slow operating relays 26 and 27. The toll operator at 100 will in this instance, instead of operating the ringing key 34, operate the dialing key 35. The operation of this key closes an obvious circuit for the operation of relays 36 and 37. The operation of relay 36 closes an obvious circuit for relay 43 which in operating closes, at its inner right-hand armature and make-beforebreak contacts; a circuit to ground for lamp 25, while relay 36 opens at its outer lefthand armature and make-before-break contacts, the circuit for relays 23 and 24 and extends at the outer armature and front contact the sleeve circuit to the marginal relay 152 associated with the dialing circuit. Relay 152 operates in this circuit and closes a circuit for relay 153 as follows: battery, Winding of relay 153, armature and back contact of relay 154, armature and front contact of relay 152 to ground. Relay 153 in operating closes a locking circuit for itself as follows: battery, winding of relay 153, winding of relay 154, right-hand arma ture and front contact of relay 153 to ground at a set of closed contacts of dialing key 35,

- which, it will be remembered, was operated to initiate the 'call on an automatic basis. Relay 37 in energizing on the operation of key 35 disconnects at its upper and inner lower armature the incoming end of the tip and ring leads of the cord circuit and extends the outgoing end of the tip and ring leads to leads 41 and 42, respectively, which are connected through. the armatures and outer contacts of relay 160 to a 1000 cycle causes the polarized rela -152 at the dialing circuit.

'300. It should be observed that relay 37 also closes an obvious short-circuit for relay 151, which in releasing closes an energizing circuit for relay 160. Relay 160 is slow to operate so that the current from the 1000 7 cycle source interrupted at the 40 cycle rate will remain on the line for a short interval only, but sufficiently long to cause certain functions to take place in the toll line equip ments preparatory to the reception of dialing impulses.

This short impulse, received through the receiving equi ment 250'in the same manner as here descri ed in connection with signals received during the ring-down connection, 256 to vibrate at the 40 cycle rate and re ay 260 to operate. This latter relay is tuned to respondonly to alternating current of the 40 cycle frequency. Relay 260 in operating short circuits relay 261 which, in turn, closes a circuit for relay 216 as follows: battery, winding of relay 216, outer left-hand armature and back contact of relay 217 to ground at the make-before-break contact of relay 261. Relay 216, in operating, provides a locking circuit for itself as follows: battery, winding of relays 216 and 217 in series, righthand armature and front contact of relay 216 to ground at the armature and front contact of relay 223. Relay 216, in operating, also removes at its left-hand armature and backcontact a short-circuiting ground for the right-hand winding of relay 202. The removal of this short-circuit increases the resistance in the sleeve circuit and thereby causes the release of the marginal relay The release of relay 152 permits relay 154 to become energized in series with relay 152 which relays are now held up by the ground at the dialing key 35 preparatory to the reception of supervlsory signals in the cord circuit indicating that the transmission of dialing impulses may be in. When the above mentioned imlay 216 to the-ground at relay 223, thus preparing this circuit for further functions in response to impulses received at the equipment 250.

The immediate effect of this short impulse of current from the 1000 cycle source interrupted at the 40 cycle rate in the iiicoming toll line equipment 300 is to cause operations to take place as will hereinafter be described. The complete circuit for this impulse to the incoming equipment 300 mav be 1 0 traced ias follows: from the source of 1000' cycle urrent interrupted at the 40 cycle rate, through the armatures and back contacts of relay 160, .the upper'and inner lower armatures and 'front contacts of relay 37, tip and-ring contacts of plug and jack 210, armatures and back contacts of relay 213,.armatures and backcontacts of relay 209, upper armature and inner lower armature and back contacts of relay 222, toll line 220, armatures and inner back contacts of relay 320 to the input transformer 352 of the receiving equipment 350, which acts, in

a manneras hereinbefore described, to cause the operation of relay 360, that in turn' short-circuits the energizing circuit for relay 361 causing it to release and connect a ground to a circuit for the energization of relay 323. This circuit for relay 323 may be traced as follows: battery, winding of relay 323, inner right-hand armature and back contact of relay 323, to ground at relay 361. Relay 323, in operating, provides a locking circuit for itself as follows: battery,

winding of relay 323, make-before-break contacts of this relay, inner left-hand armature andback contact of relay 324 to ground. The operation of. relay 323 also connects battery to the winding of relay 303, causing this relay to operate as follows: battery, outer right-hand armature and front contact of relay 323, winding of relay 303 to 322 as will be presently described. It should be noted that relay 323 in operating also establishes a busy potentialon the sleeve of jack 314 from battery at its outer righthand armature and front contacts. In addition the operation of'relay 323- closes at its outer left-hand armature and front contact to permit marginal relav 416 to operate in a circuit from groundat the make-beforebreak'contacts of-relay 362 to the automatic exchange equipment for the conditioning of this equipment for extension of a call as follows: battery to the slow-to-release relay 406, winding of this relayfarmature and back contact of relay 407. lead 450, inner left-hand armature and back, contact of relay 325, outer left-hand armature and front contact'of relay 323 to ground at the make-before-break contacts 7 of, relay 362. This causes the operation of relay 406 which in turn causes the slow-to-releaserelay 408 to operate over an obvious circuit and this relay establishes an obvious energizing circuit for relay 411. At its inner right. hand armature, relay 411 establishes a circuit for relay 407 whic'hmay be traced fie-"8m battery,

winding of relay 407, conductor 462 to ground over the front contact and inner right hand armature of relay 411. Relay 407 in attracting its armature opens the original energizing circuit for relay 406 which relay thereupon releases, removing the original ground from the winding of relay 408 which, however, now remains operated in a circuit extending from battery through the winding of relay 408, armature and front contact of relay 407 to ground over lead 450, outer left. hand armature and back contact of relay 325, outer left hand armature and-front contact of relay 322 to round at the 'make-before-break contacts of relay 362. At its outer left hand armature, relay 411 prepares a circuit for relay 414 and at its inner left hand armature prepares a circ'uit for

relays

422 and 416. At itsouter right hand armature, relay 411 prepares a circuit causing the start magnet 412 to operatewThis circuit extends from battery through winding of magnet 412, outer right hand armature and back contact of relay 414, armature and back contact of relay 416 to ground at outer right hand armature and front contact of relay .411. Magnet 412 causes the rotary magnet 418 to operate in an obvious circuit. The rotary magnet 418 in operating causes the line switch F. to start hunting for an idle district switch in a manner well known in the art.

iwhen an idle district switch such as is diagrammatically indicated at Gr is reached, the idle condition thereof being designated by the presence of battery on the test terminal thereof, relay 422 operates in a circuit extending from battery, contacts of sequence.

switch spring 440, armature and back contact of relay 425, terminal 420 and wiper 421 of line switch F, front contact and in- -ner left hand armature of relay 411, both windings of relay 422 to ground through the winding of relay 416. Relay 422 in attracting itsarmature short-circuits its own right hand winding thereby reducing the resistance in the circuit just traced, sufliciently series with relay 422. Relay 416 upon energizing causes cut-off relay 414 to energize in a circuit extending from battery winding of cut-off relay 414, front contact and armature of relay .416 to ground at the outer right hand armature and front contact of relay 411. Relay 414 in attracting its outer right hand armature opens the energizing circuit for magnet 412 whereupon this magnet restores, causing the rotary magnet 418 torrelease. At its inner right hand armature relay 414 prepares a circuit for relay 427 for supervisory purposes which will hereinafter appear. In attracting its outer left hand armature, relay 414 looks up under the control of relay 411, and at-its two inner armatures 423 and" 424 closes through the tip and III ring leads to corresponding terminals of switclTf F for purposes hereinafter to be set forth. At its inner left hand armature, relay 414 closes an energizing circuit for relay 425' from batter winding of relay 425, terminal 475 an wiper 441 of line switch F to ground at this inner left hand'armature and front contact of relay 414. Relay 425 in attracting its armature removes battery from the test terminal 420 of line switch F, whereupon relays 416 and 422 release, the former opening the original energizing circuitfor relay 414 which, however, remains locked.

The operation of the control relay 425 oftheselected district switch causes an idle sender to be selected in the well-known manner whereupon relay 500 operates causing relay 501 to operate through intermediary relays (not shown) to cause a dialing signal to be given to the operator at 100 in the following manner. Relay 501 in operating places a ground on the tip conductor of the line switch F. This ground causes relay 427 to operate in a circuit extending from battery through the winding of relay 427, inner right-hand armature and back contact of relay 428, contacts 423 of relay 414, wiper 498 and contact 431 of switch F, lowor left-hand contacts of sequence switch spring 480 (1+16), upper right-hand contacts ofsaid spring (2 44-10) to ground at the contacts of relay 501. Relay 427 in operating causes the ground at relay 411 to be connected to lead 451 which causes the operation of relay 326 as follows: battery, at outer. right-hand armature and back contact of relay 324, winding of relay 326, lefthand armature and back contact of relay 327, lead 451,'armature and front contact of relay; 427, inner right-hand armature and front contact of relay 411 to ground. This relayin operating provides a locking circuit for itself from battery at the relay 324 in series with the Winding of relay 327 and inner left hand armature and front contact of relay 326 to the ground at the inner lefthand armature and back contact of relay 324. Relay 327 does not, however, operate at this time as it is short-circuited by ground on lead 451. The operation of relay 326 causes the release of relay 328 by opening at its outerleft-hand armature and back contact an obvious energizing circuit for this relay. \Relay 328, in releasing. causes the operation of relay 362 from battery, winding of relay 362, right-hand armature and back contact of relay 327, right-hand armature and back contact-of relay 328 to ground. The operation of relay 362 removes the ground for the lead 450 at its make-beforebreak contacts and connects this lead to ground at the armature and back contact of relay 329. -Relay 329 is controlled from the receiving circuit equipment 350 which now IS in condition to control the automatic equipment for the reception of dialing impulses.

It. should be noted also that relay 326. causes a short impulse of current from the 1000 cycle alternating current source interrupted at the 40 cycle rate to be connected to the toll line 220, the outgoing toll line equipment 200 and the cord circuit at 100 to the 1000 cycle source interrupted at the 40 cycle rate, to be connectedto the line 220 through its left-hand armatures and front contacts. A signal from this-source is, therefore, received at the receiving circuit equipment 250 over the following circuit: from the 1000 cycle current interrupted at the 40,

cycle rate through the left-hand armatures andback contacts 'of relay 346, left-hand armatures and front contacts ofrelay 345, upper and lower armatures and inner back contacts of relay 320, toll line 220, upper and inner lower armatures and back contacts of relay 222, upper and lower armatures and inner back contact of relay 209 to the primary winding of the input transformer 252. f This impulse through the receiving equipment 250, in the manner as heretofore described to cause the operation of relay 260, which in turn, causes the short-circuiting of relay 261. As relays 216 and 217 are locked up, a path is provided for the circuit from the ground at relay 261 to the mid-point of the wind ing of relay 202 and relay 261 will, therefore, in releasing apply a short-circuiting ground for the right-hand winding of relay 202 and thereby cause the resistance in the sleeve circuit to be decreased. The marginal relay 152 is consequently operated to cause lamp 25 to be lighted in the following man ner: It will be remembered that relays 153 and 154 are operated and the operation of relay 152 will, therefore, at this time cause the operation of relay 155 over the following circuit: battery, right-hand winding of relay 155, armature and front contact of relay, 154, armature and front contact of relay152 to ground. Relay 155, in operating, provides a locking circuit for itself as follows:. battery, left-hand winding of relay 155, left hand armature and front contact of relay 155, armature and back contact is effected of relay 158, left hand armature and front I contact of relay 153, off-normal contacts 156 of the operators dial. 157 to ground. Re-

lay 155 also completes the circuit for lam 25 from battery, right-hand armature an front contact of relay 155, inner left-hand armature and front contact of rela 36, lamp 25, make-before-breakcontacts o relay 42 to ground. The lighting of lamp 25 serves as an indication to the operator at 100 that .162 in series, armature and front contact of relay 161, left-hand armature and front contact of relay 153 to the ground at the oif-normal contact of relay 156. Relay 162,

- however, does not operate immediately, that is, not as long as it is short circuited by the ground at the armature and front contact of relay 152. However, it will be remembered that the impulse of 1000 cycle current interrupted at the 40 cycle rate is of short duration so that when it ceases and relay 152 is released, this relay 162 operates and is locked up in series with relay 162 to ground at the oflhnormal contact 156.

During the momentary operation of relay 345 as described above, the signal current from the 1000 cycle source interrupted at the 40 cycle rate transmitted over the toll line to give the dialing signal is also transmitted to the receiving circuit 350, causing the momentary release of relay 361. Al-

though the ground applied to the leads from the make-before-break of this relay is delayed as compared with the operation of Y relay 345, this ground, nevertheless, will be applied in time to hold relay 322 operated, while relay 345 is operated as relay 322 is slow in releasing and consequently will be kept from releasing on the operation of relay 345. The circuit for holding relay 322 operated during the operation of relay 345 is as follows: battery winding of relay 322, inner right-hand armature and front contact of relay 323 to ground at the inner right-hand make-before-break contacts of relav 361. The function of relay 322 in the subsequent operations of the circuit will be described later.

, Current from the 1000 cycle source in the dialing circuit 150 is now in position to be connected to the receiving circuit 350 as a the removal of groundcat the off-normal contacts 156 from the locking circuit of re lay 155. As the original energizing circuit for this relay was broken at the release of relay 152, this relay releases and thus causes the lamp 25 to be extinguished and it is obvious that this lamp cannot be again operated by any operations on the part of the dial as relay 155 in releasing opens at itsleft hand armature and front contact the circuit leading from this relay to the ground at contacts 156. Relays 161 and 162 are also released at the operation of the dial from normal and cannot again be locked up except through operations initiated by relay 152 as will be hereinafter described. The second effect of the actuation of the dial 157 in accordance with the number of the desired line is that ground is connected to the Winding of relay 163 from the off-normal contact 156 of the dial, causing the relay 163 to operate over an obvious circuit. Relay 163 connects at its armature and front contact one lead from the 1000 cycle source to lead 42, which, as hereinbefore described, extends with lead 41 through the armatures and front contacts of relay 160 to the armatures of relays 163 and 164.

The pulsing contactsl57 of the dial open for each pulse during the return movement of the dial to normal and thereby cause the relay 164 to release over an ObVlOllS circuit and connect the other lead from the 1000 cycle source to lead 42. In this manner pulses are transmitted to the distant end the circuit for relay 329 which in operating causes selecting operations to be performed by the automatic exchange equipment shown in Fig. 4. That is, the operation of relay 329 disconnects the ground from lead 450 and relay 500 responds to the impulses. The circuit for this relay is as follows: battery, winding of pulsing relay 500, lower righthand contact of sequence switch spring 493 (3+10 upper left-hand contact of this sequence switch spring (1+16), contact 432 and ring wiper 445 of line switch F, contacts 424 of relay 414; back contact and outer right-hand armature of relay 428, armature and front contact of relay 407, lead 450, inner left-hand armature and back contact of relay 325, outer left-hand armature and front contact of relay 323, armature and frontcontact of relay 362, to ground at the armature of relay 329. When ground is remoyed from relay 329 in accordance with the interruptions of the dial contact,'.the

round is also removed from the rela 408.

owever, this 16183 remains operated uring the dialing perio owing to its slow releasing characteristics. It should also be noted that due to the slow releasing characteristics of relay 322 this relay will not be releasedon the repeated operation of relay 329 during the dialing period as the time this relay operates for each impulse is governed by the speed of the dial in returning to normal, and this speed is such that relay 164 will'only be released for periods suitable for accomplishing this result.

To'turn now to the operationof the automatic exchan e equi ment when all the pulses are reglstered 1n the sender, ground is removed from the tip lead at relay 501, thereby causing relay 427 to release which in turn opens the circuit to ground over lead 451. This ermits the operation of relay 327 in series with relay 326 from ground applied at the inner left-hand armature and back contact of rela- 324. The operation of relay 327 causes t e release of relay 362 which thereby causes the dialing lead 450 connected to ground at relay 329 to be broken at its left-hand armature and front contact and the ground at its makebefore-break contact is substituted therefor to maintain the sender relay 500 energized for the time being.

When the wanted subscribers line at 410 is reached, a ground is connected at the contact 429 from sequence switch contact 485 to wiper 438 of the line finder switch If, whereupon relay 428 is operated in a circuit which may be traced from battery, winding of relay 428, contacts 437, contacts 439 of relay 414, wiper 438 and terminal 429, contacts 485 to ground. Relay 428 looks up through its contacts 447 to ground under control of relay 414. At its inner righthand armature, relay 428 disconnects relay 427 from the tip lead and at its inner lefthand armature and front contact, connects relay 427 to the wiper 438 of the line finder switch F to ground at 485. At its outer left-hand armature, relay 428 establishes a circuit for relay 330 which may be traced from battery, winding of relay 330, lead 452, outer left-hand armature and front contact of relay 428, conductor 462, and inner right-hand armature and front contact of relay 411 to ground. Relay 330 looks up over its inner lower armature and front contact through lead 453 as it should be noted that this lead also received ground from the inner armature and front contact of relay 411 over lead 462. The operation of relay 330 performs no useful function at this time. The ground on lead 452 from relay 411 causes the operation of relay 331 from battery, winding of relay 331 to ground on conductor 452. The operation of relay 331 'is not used on this type of connection and is therefore of no significance. The use in another ty e of connection will be described later. Re ay 332 which is slow to release determines the length of this impulse and is released by the operation of the lower armature and back contact of relay 331 The

relays

330 and 332 therefore connect the tip and ring'conductors' from the automatic equipment through to the toll line 220 in a manner which it is considered requires no further explanation. The ground on lead 452 also causes the operation of relay 471 from battery, winding of relay 471 make-before-break contacts of relay 471 to ground on. lead 452. Relay 471 then locks up to ground on lead 453 and prepares a circuit for future rin or rering operations.

If the wanted su scribers line is idle, the ground connected at 429, now due to the operation of relay 428 causes the operation of relay 427 over the following circuit: battery, winding of relay 427, inner lfthand armature and front contact of relay 428, contacts 439 of relay 414, wiper 438,

contact 429 to ground at 485. The energiza- 345. Relay 345, in operating, again conmeets the 1000- cycle current source, current from which is interrupted at'the 40 cycle rate, to the toll line 220. The receiving circuit corresponding to this impulse again causes the release of relay 261 which applies a short-circuiting ground to the righthand winding of relay 202. If this operation occurs before the dialing key is released, relays 153 and 154 are still operated so that when relay 152 responds, due to the decrease in resistance of the sleeve, the circuit for relay 155 is completed and lamp 25 is therefore lighted to indicate to the operator at that the called subscriber is idle and that ringing operations may begin.

When all the digits corresponding to the number of the desired line have been dialed, the operator at 100 ordinarily restores the dialing key 35 immediately and thereby re leases relays 36 and 37 but leaves relay 43 energized for the time being. The release of relay 37 disconnects the dialing circuit 150 from the operators cord circuit by causing the release of relays 153 and 154. The release of relay 36 breaks the energizing circuit for relay 43, but this relay, being slow releasing, is provided with a holding circuit from the armature and front contact of relay 24 which operates in series with marginal relay 23 over the sleeve circuit as soon as relay 36 is deenergized and lamp 25 is, thci'eforc, maintained energized as it receives battery from the armature and front contact of relay 23.

As the operator at 100 is now connected through the automatic equipment to the wanted subscribers line, she may signal the subscriber by the operation of key 34 and the circuit functions in a manner similar to that described in connection with calls extended on the ring-down basis except as follows: I .'I

In this case, the automatic equipment at 200 operates in response to the 20 cycle current and ground from the source at'th'e key 34 to transmit over the line 220 a short im.

pulse of current from a 1000" cycle source followed by current from a 1000 cycle source interrupted at the 20 cycle rate. The operation in t is respect is as follows Upon the operation of relay 208;an ener-' 'zing circuit is established'for' relay 226 i'om battery, winding of relay 226, righthand armature and front contact of relay 217,1eft-hand armature and front contact of relay 208 to ground. Relay 226 in. operating closes an obvious circuit for-relay 209 and an impulse from the 1,000 cycle source is therefore transmitted over the line as follows: the 1,000 cycle source to the righthand armatures and back'contacts of relay 225, inner left-hand armature and front contact and right-hand armature and front con-' tact of relay 226 through thearmatures and front contacts of relay-209 to the line 220. The operation of relay 226' also opens the obvious energized circuit for slow-to-release relay 227 which in releasing closes an obvious energizing circuit for relay 225. Re

lay 225 in operating removes at its right-- line 220 has the effect in the equipment at 300 of discontinuing the transmission of current from the 1,000 cycle source interrupted at the 40 cycle rate which, it will be remembered, is transmitted to the line through relay 345 that operated when the called subscribers line was found idle; i. e., relay 356 is operated through the receiving equipment 350 as hereinbefore stated to cause the operation of relay 329 over an obvious circuit. The operation of relay 329 closes a short circuit to ground for relay 322 which in releasing closes an obvious energiz- The short iming circuit for rela 346. Relay 346 in opcra'cing provides a ocking circuit for itself through its inner right-hand armature and front contact, outer left-hand armature and bark contact of relay 324 and make-beforebreak contacts of relay 347 to ground. Relay 346 also removes at its left-hand armature and back contact, current from the 1,000 cycle source interrupted at the 40 cycle rate. This impulse of 1,000 cycle current is now followed by current from the 1,000 cycle source which is interrupted at the 20 c cle rate. This current is effective through t e receiving circuit at 350 to cause the operation of relay 357 which in turn closes at its armature and contact a short circuit for relay 358 which in releasing closes at its make-bcfore-break contact a circuit for relay 347 as follows battery, winding of relay 347, inner left-hand armature and front contact of relay 326, make-before-brcak contacts of relay 358 to ground. Relay 347 in operating transfers the locking, circuit for relay 346 from the ground at its makebefore-break contacts to the ground at the make-before-break contacts of relay 358 so that relay 346 is maintained operated as long as the ringing key 34 is operated. Relay 347 also closes at its right hand armature and front contact a circuit for relay 499 in the .automatlc equipment as follows: battery,

winding of relay 499, sequence switch contacts 494, terminal 496, wiper 497, righthand armature and front contact of relay 471, lead 454, right-hand armature and front contact of relay 347 to ground. The operation of relay 499 causes'the application of.

ringing current from the source 492 over this established connection to actuate the called subscribers bell.

When the called subscriber answers in response to the ringing signal by removing his receiver from the switchhook, ground is removedfrom the contact 485 at the switch F, thereby opening the circuit for relay 427. Relay 427 in releasing, opens the circuit for delay 345 causing lamp 25 at the o erators position at 100 to be extinguishe by the release of the marginal relay 23 as hereinbefore described to indicate to the OMEIal'OI that the subscriber has answered. onversation may now begin between the subscriber at 10 and the subscriber at 410.

At the termination of the conversation, the subscriber at 410 upon replacing the receiver on the switchhook again causes ground to be placed on the terminal 429 of switch F from contact485, thereby causing the energization of relay 427. Relay 427, in operating, causes ground from relay 411 to be connected to lead 451 causing the reenergization of relay 345 and the consequent a plication of current to the toll line from tl ie 1,000 cycle source interrupted at the40 cycle rate. This, in turn, as 'hereinbefore described, causes the lighting-of lamp, 25 by at 100 and she proceeds to take down the connection by withdrawin plug 15 from jack 210. As a result of t is action, relays 24, 23 and 202-are immediately released. The release of relay 24 causes the release of relay. 43 and the extinguishing of lamp 25. The release of relay 202 causes a short signal from the 1,000 cycle source followed by a short signal from the 1,000 cycle source interrupted at the 40 cycle rate, to be sent to the Incoming toll line equipment 300 and the restoration of the outgoing toll line equipment 200 to normal. This procedure- 18 as follows: a circuit is closed for relay 224 from battery, winding of relay 224, outer right-hand armature and front contact of relay 203, inner right-hand armature and back contact of relay 202 to ground. The operation of relay 224 connects the 1000 cycle source, current from which is interrupted at the 40 cycle rate, to the front contacts associated with the right-hand armatures of relay 225. It also closes an obvious energizing circuit for relay 226. Relay 226, in operating, connects at its inner left-hand armature and right-hand armature and front contacts the 1,000 cycle current source normally connected at the right-hand armatures and back contacts of relay 225 to the front contact associated with the armatures of relay 209. This relay 226 also closes at its middle left-hand armature and front contact an obvious energizing circuit for relay 209 and opens at its outer left-hand armature and back contact the obvious energizing circuit for relay 227. The operation of relay 209 opens the tip and ring leads of the toll line and connects them through the armatures and front contacts to the 1,000 cycle source. Relay 227 which is slow in releasing closes after a short period the obvious energizing circuit for relay 225 which in operating transfers the leads to the outgoing toll line 220 from the 1,000 cycle source to the'1,000 cycle source, current from which is interrupted at the 40 cycle rate. The operation of relay 225 also opens the energizing circuit for relay 223. Relay 223 which is slow to release opens after a short period the locking circuit for relays 216 and 217. These relays then release and cause the release of relay 203 which restores the busy signal 205 to normal and opens the energizing circuit for relay 224. Relay 224 in relasing causes the release of

relays

226 and 209, the reoperation of relay 227, the release of relay 225 and the reoperation of relay 223. This series of operations cause as stated an impulse of 1,000 cycle current followed by an impulse of 1000 cycle current interrupted at the 40 cycle rate to be sent out. over the toll line 220 to the incoming equipment 300. The impulse of 1000 cycle current causes the operation of relay 356 in the receivlng equipment 350 and the consequent operation of rela 329 which in turn, short-circuits. the winding of relay 322 by closing a circuit to ground at its armature and front contact. Relay 322, in releasing closes an energizing circuit for relay 346 whlch operates and locks up to ground at the make-before-break contacts of relay 347 over the following circuit: battery, Windmg of relay 346,'inner right-hand armature and front contact of relay 346, outer lefthand armature and back contact of rela 324, make-before-break contact of relay 34 to ground. The operation of relay 346 opens at its left-hand armatur and back contact the leads from the 1000 %'cle source current from which is interrupt d at the 40 cycle rate, and thus discontinues the application of current from this source to the line. In other words, a signal of a steady current from the 1000 cycle source incoming over the toll line prepares the receiving equipment 300 for the reception of a distinctive disconnect signal of the same character as the outgoing disconnect signal present on the line. Theimpulse of 1000 cycle current interrupted at the 40 cycle rate that immediatly follows causes the release of relay 261, which in releasin closes a circuit for relay 348 as follows: attery, winding of relay 348, outer right-hand armature and front contact of relay 346, outer right-hand makebefore-break contacts of relay 361 to ground. Relay 348 operates and locks up in series With the left-hand winding of relay 324 to the ground at the outer left-hand armature and front contact of relay 323. Relay 324 does not operate immediately due to the short circuiting ground at the make-beforebreak contact of relay 361, but as soon as the impulse of 1,000 cycle current interrupted at the 40 cycle rate ceases relay 361 operates and relay 324 is operated first on its lefthand Winding in series with relay 348 and then looked up on its right-hand winding to the ground on lead 451. The locking circuit for relay 324 may be traced as follows: battery, right-hand winding of relay 324, inner right-hand armature and front contact of this relay, lead 451, armature and front 'contact of relay 427, inner right-hand armature and front contact of relay 411 to ground. Relay 324 in operating opens at its inner left-hand armature and front contact, locking circuit for relay 323 and in addition at its outer right-hand armature and back contact the circuit for relays 327 and 326- Relay 327 in releasing opens the circuit of relay 345 while relay 326 in releasing causes the reoperation of relay 328 which thus prevents the operation of relay 362. Relay 323 in operating releases relay 348,by breaking its energizing circuit in series with the lefthand winding of relay 324, through its outer left-hand armature and front contact. Relay 323 in releasing also opens atrits middle left-hand armature and front contact .a ground connection for lead 450 so that relay 408 releases after an interval and. opens the energizing circuit for relay 411. Relay 411 in' retracting its outer left-hand armature, opens the locking circuit for rela 414 which relay thereupon releases. -At its inner righthand armature-relay 411 disconnects ground from the windings of relays 407 and 471 whereupon these relays release. Relay 471, in releasing, opens the normal energizing circuit for relay 499. The restoration of the automatic equipment now takes place in the manner well known in the art.

It, in the course of completion of the connection by the automatic exchange equipment all trunks for extending the connection are found busy, intermittent ground is connected to the terminal 429, from an interrupter such as 483 or any other suitable means, at a certain rate, for example, 60 interruptions per minute. The first impulse tov ground will operate relay 428- and the following ground operate relay 427 which thereafter will be interrupted at the corresponding rate to alternately close and open the circuit for relay 345. This relay will consequently alternately connect and disconnect the source of 1000 cycles interrupted at a 40 cycle rate to the toll line 220 and the lamp 25 will therefore be intermittently lighted at interruptions per minute in a manner which is believed to be obvious. The flashing of this lamp indicates to the operator that all trunks are busy. However, there is a slight diti'erence in the operation of the relays in the dialing circuit 150 in this case from previous operations in that when the first impulse is received to cause the operation of relay 152, ground at this relay causes the operation of relays 155 and 161 and when this impulse ceases, relay 155 is locked up to ground at the off-normal contacts 156 of dial 157, while relay 162 operates and locks up in series with relay 161 to the elf-normal contacts 156. In order to free relay 155 from this locking circuit and cause it to respond to succeeding impulses and thus cause the flashing of lamp 25, relay 158 is provided. Itwill be noted that on the second impulse, causing the operation of relay 152, the relay 158 is operated through the armature and front contact of relay 162 and as it is slow to release as compared with relay 155, the locking circuit for relay 155 will not be closed when the second impulse ceases and relay 152 is released. Consequently, relays 155 and 158 will respond each time and down during the talking'period. Relay 345 is operated when the switchhook is down and released when the switchhook is up.

If the operator at 100 desires to rerin the called subscriber after he has replace his receiver on the switchhook, she operates the ringing key 34 and the circuits function in exactly the same manner as when the wanted subscribe-r was first called, that is,

the impulse of steady current from the 1000 cycle source causes the operation of relay 329, the release of relay 322 and operation of relay 346 which disconnects the sending of current from the 1000 cycle source, interrupted atthe 40 cycle rate, to the outgoing equipment and the cord circuit at 100 where such current, as has hereinbefore been described, maintains the lam 25 lightedas a disconnect signal. Shoul the 1000 cycle impulse be of such short duration that relay 322 which is slow-to-release not release as described above its release is insured by same incoming 1000 cycle impulse upsetting the operation of relay 360. This will permit relay (361) to operate and in this way release relay (322) by removing ground from its winding. The impulse of 1000 cycle current interrupted at the 20 cycle rate that follows the steady impulse of 1000 cycle current is now received through the equipment 350 and causes the release of relay 358. A ground from this relay causes the operation of relay 347, which in turn, applies ground to the lead 454 and the circuit for relay 499. The operation of relay 499 causes the application of ringing current from the source,

492 to the established connection to resignal the wanted subscriber. Relay 347 in operating also removes the holding ground for relay 346 at its makebefore-break contact and transfers this holding circuit for ,relay 346 to the ground at relay 358. When therefore relay 358 is again released as the impulse of 1000 .cycle current interrupted at the 20 cycle rate ceases, the holding circuit for relays 346 and 347 is opened causing these relays to release as relay 346 is faster in releasing than relay 347. It will be seen therefore that 1000 cycle current, interrupted at .40 cycles will be again transmitted over the line to'light lamp 25 when the reringing \Q signal ceases and this signal will remain on the line until the called subscriber answers the second time when it is extinguished as hereinbefore described.

In case an automatic call extended from the automatic equipment is not intended for a subscriber, such as the one connected at 410, but for a subscriber that may be reached through the medium of another toll line, i. e. if a terminal bank, for example, the one represented by terminals 510, is reached by the brushes of the switch 511 and these terminals are connected to a toll line leading to another distant exchange and a subscriber in another exchange is the one desired, the automatic equipment at Flg. 4 will then merely serve for a so-called through connection. The equipments associatedwith this second toll line may be identical with that shown in Figs. 2 and 3 which may also serve for a through connection and would in that case be reached from a switch such as 275 making contact with terminals 276 of this toll line.

The operator at 100 will, in the case of a through connection not only dial a number that will bring the connection up to the terminals 510, but also an additional number for the desired subscriber in the second automatic exchange. The first function after the connection has been extended to terminals 510 in response to the first number, will then be the transmission over the second toll line for a short period of current from the 1000 cycle alternating current source in-,

terrupted at a 40 cycle rate as has hereinbefore been described at the operation of relay 331. This short application of current conditions the second distant exchange for receiving impulses from the operator at 100 representing the second number and it can be seen that as previously described when relay 332 operated the talking leads 455 and 456 will be extended to the toll line 220 at the upper and ,lower make-before-break' contacts of relay 332.

Leads

455 and 456 are then also, of course, connected over the second toll line to a second distant exchange upon receipt of a signal indication from the distant toll line equipment to indicate that the second number may be sent in the same manner as hereinbefore described in connection with the extension of a call t'd an automatic subscriber through the-i'equipment at 300 and Fig. 4. The operator at 100 may now therefore proceed in dialing the second number and the procedure will be the same as has already been describedin connection with the extension of a call to the subscriber at 410. It should be stated that a relay similar to relay 222 is operated to discon- ,nect the corresponding outgoing toll line equipment such as that shown at 200 from the second toll line. No further description the energization of relay 341. Relay need be made as the following fimctions are exactly the same at the second distant exchange as has been previously described in connect-ion with a call over the toll line 220. It is, therefore, seen that the toll line equi ment as arran ed in accordance with this invention may be utilized for through automatic connections as well as terminatin automatic terminating manual or througE manual connections. a

It now only remains to consider one more type of connections that may be extended by the use of this toll line equipment, namely a call intended for what is commonly as an out-delayed operator, i. e., an operator having e uipment arranged in a manner similar to t eoperator at 310 only that this operator is reached by having the o'p-- erator at 100 diala certain number of special code. In this case the operator at 100 proceeds in the same manner as when dialing for an automatic subscriber such as the one located at 410 only instead of reaching subscribers line terminals she will be connected to terminals such as 515, connected directly to a ground andbatte This battery and ground is transmitted ack over the line and will cause the operation of relay 516. Relay 516 in operating causes ground to be connected to lead 457 resulting in the operation of relays 325 and 341 over the following circuit: battery, left-hand winding of relay 325, lead 457 to round at relay 516 for the energization o relay 325 and battery to the left-hand winding of relay 341, lead 457 to the ground at relay 516 for 341 provides a locking circuit for itself from battery, through the right-hand winding of this relay and its right-hand armature and front contact to ground at the inner upper armature and back contact of relay 342. This relay 341 at its left-hand armature and front contact closes an obvious circuit for the signal 343 which is thereby operated and indicates to the out-delayed operator that a connection is desired by the line associated with jack 344. Relay 325 rovides a looking circuit for itself from attery, through its right-hand winding and inner right-hand armature and front contact to ground at the inner left-hand armature and back contact of relay 324. This relay 325 also prepares a locking circuit for relay 349, the purpose of which will be hereinafter described and at its iner left-hand armature and back contact removes the ground connection at relay 362 for lead 450 which causes the automatic equipment in Fig. 4 to be released to normal as hereinbefore described. When the outdelayed operator in answer to the lighting of lamp 343'inserts the plug of her cord circuit into jack 344, relay 342-is operated in the well known manner and the operation of this relay opens the locking circuit for ,and outer ri ht-hand armature and front contact of re ay 325 winding ofrclay 349 to battery. Relay 342 also dlsconnects the tip and ring leads to jack 314 from the line,

, whereas relay 349 causes the operation of ..relay 303 over an obvious clrcuit. The operation of relay 303 causes the operation of busy signals 304 and 305 as herembefore described. The connection between the operator at 100 and the out-delayed operator isnow completed and conversation may take place.

. It should be noted that in the ei ent the Font-delayed operator is used in through connection the operator at 100 may supervisorysignals to th1s operators cord circuit, by virtue of thQQPGIfitlOIl of relay 303 or through the connection completed at [as v the outer left-hand armature and front consend tact of relay 325v by operations as hereinifli flbefore described thatwill result in the re *lkaase of'relay; 358, that is, relay 340 w1ll be operated over a circuit as follows: battery,

winding of relay340, outer left-hand armature and front contact of-relay 325, righthand armature and front contact of relay 347 to ground if relay323 is operated when as I energized, or from battery at relay 340 relay 358 is released as relay 347 is then through the inner left-hand armature and front 'contact o'f relay 303fin-ner left-hand armature and back contact of relay 323 If released at this, time toground at; relay 358.-

' *currents to indicate that the subscribers The pperation'ofrelay 340 as hereinbefore ,described, connected .current from the cycle source and ground to the tip and ring .leads connected through jack 344. to cause the operators cord circuit at 311-to lig ti the supervisory lam in do so by moving her plugin and out of jac 344, thus causing the momentary release at relay 342 which will then completea circuit for relay 326 from battery, winding of relay 345, inner left-hand armature and front con j tact of relay 345,'inner"right-hand armature 1 and front contact of relay 349 inner lower, armature and backjcontact of relay 342 to ground; The operation of relay: 345 will then, as-hereinbefore described, connect cur"- rent from the 1000' cycle source, interrupted at the .40 cycle rate and cause the flashing of' "lamp at 100 at the'rate at which the out-delayed operator plugs in and out of. jack 344. If the out-delayedoperator ,de-r

sires to break the connection she removes her plug from jack 344. This. causes lamp 25 .istation, si

e d-- 1 11 3. In' a telephone system,- the'combination to be maintained lighted to serve as a designation for the operator 100 to disconnect which she proceeds to do as hcreinbefore described.

What is claimed is:

' 1. In a telephone system, the combination of subscribers stations with a toll line terminating in means for extending the line auto- -matically to a subscribers station, means at the terminating end of said line for transmitting back over the line high frequency alternating currents periodically at a certain rate actuated when an automatic connection has been extended to a subscribers station, signaling means at the originating end of the a line responsive to said alternating currents to indicate that the subscribers station has .been reached, means at the originatin end for transmitting over said line a call s1 nal, signaling means at the terminating en for calling the connected subscribers station,

alternatingccurrents periodically at a cer- I tain rate actuated when an automatic connection has been extendedto a subscribers aling means at, the originating end of the ine responsive to said alternating station has been reached, means at the originating endfor transmitting over said line a call. signal, 'si nali'n 'means at the terminating end for calling t e. connected subscribers y v station, means at the terminating ,end re- 7 In'case the" out-delayed? .:operator' de-. sires tel'recall the operator at 100 she ma sponsive. to "said call-signal for discontinumg the transmissionof alternating currents T to the originating end, and then actuating the signaling means at this end of the line 7, means for continuing the transmission of alternating currents to the originating .end when the call signal ceases, and means actuated when the subscriber at the called station answersfor" discontinuing the transmission ofaalternatingc'urre'ntsjto the originating of, .subscribers stations with a toll, line terf'minating in means for extending the line automatically to a subscribers station, means-at the [terminating end of said line for transmitting back' over the line hi -h frequency alternating currents periodically at-a certain rate actuated when an automatic Ill connection has been extended to a subscribers station, signaling means at the originating end of the line responsive to said alternating currents to indicate that the subscribers station has been reached, means at the originating end for transmitting over said line a call signal comprising alternating currents of the same frequency applied periodically at different rates, signaling means at the terminating end for calling the connected subscribers station, means at the terminating end responsive'to said call sig nal for discontinuing the transmission of alternating currents to the originating end and then actuating the signaling means at this end of the line, means for continuing the transmission of alternating currents to the originating end when the call signal ceases, and means actuated when the subscriber at the called station answers for discontinuing the transmission of alternating currents to the originating end.

4. In a telephone system, the combination of subscribers stations with a toll line terminating in means for extending the line automatically to a subscribers station, means at the terminating end of said line for transmitting back over the line high frequency alternating currents periodically at a certain rate actuated when an automatic connection has been extended to a subscribers station, signaling means at the originating end of the line responsive to said alternating current to indicate that the subscribers station has been reached, means at the originating end for transmitting over said line a callsignal comprising an impulse of alternating current of the same frequency followed by impulses of the same frequency applied at a different rate, means at the terminating end responsiveto the signal impulse of the call signal for discontinuing the transmission of the alternating current to the originating end, signaling means at the terminating end responsive to the remainder of the call signal for calling the subscriber at the connected substation, means for continuing the transmission of alternating currents to the originating end when the call signal ceases, and means actuated when the subscriber at the called station answers for discontinuing the transmission of alternating current to the originating end.

5. In a telephone system, the combination of substations with a toll line terminating in means for extending it automatically to a subscribers station, means at the terminating end of said line for transmittng back over the line high frequency alternating currents periodically at a certain rate actuated when an automatically connected subscriber hangs up his receiver, signaling means at the originating end responsive to said alternating currents, means at the originating end for transmitting over said line a disconnect signal, means at the termlnatmg end responsive to said signal for discontinuing the transmission of alternating currents to the originating end and then restoring the automatic means to normal.

'6. In a telephone system, the combination of substations with a toll line terminating in means for extending it automatically to a subscribers station, means at the terminating end of said line for transmitting back over the line high frequency alternating currents periodically at a certain rate actuated when an automatically connected subscriber hangs up his receiver, signaling means at the originating end responsive to said al ternating currents, means at the originating end for transmitting over the line a signal comprising an impulse of alternating current of the same frequency followed by im-' pulses of the same frequency applied at the same rate, means at the terminating end responsive to the single impulse for discontinuing the transmission of the alternating current to the originating end, 'and means at the terminating end responsive to the remainder of the signal for restoring the automatic means to normal.

7. In a telephone system, the combination of substations with a toll line terminating in means for extending it automatically to a subscribers station, means at the terminating end of the toll line for transmitting back over the line high frequency alternating currents interrupted at a certain rate in groups of such impulses at various intervals actuated when an automatic connection cannot be completed either due to a busy condition of the ch0sen path to the wanted subscribers station at which time the groups of impulses are transmitted at certain intervals or due to the busy condition of the wanted subscribers station itself at which time the groups of impulses are transmitted at certain other intervals, signaling means at the originating end responsive to said alternating current in a distinctive manner to either of said busy conditions, means at the originating end for transmitting over said line a signal, and means at the terminating end responsive to said signal for discontinuing the transmission of alternating current to the originating end and then restoring the automatic means to normal.

8. In a telephone system, the combination of substations with a toll line terminating in means for extending it automatically to a subscribers station, means at the terminating end of said line for transmitting back over the line high frequency alternating currents interrupted at a certain rate in groups of such impulses at various intervals actuated when an automatic connection cannot be completed either due to a busy condition of the chosen path to the wanted subscribers