US1543665A

US1543665A - Alarm system for automatic telephone exchanges

Info

Publication number: US1543665A
Application number: US609571A
Authority: US
Inventors: Roy D Conway
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1922-12-29
Filing date: 1922-12-29
Publication date: 1925-06-30
Anticipated expiration: 1942-06-30

Description

June 30, 925. 1,543,665

R. D. CONWAY ALARM SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES /m/eW/ar' /ay 0mm/4 y Wfl/y'.

June 30, 1925.

2 Sheets-Shaka?.

Filed Dec. 29, 1922 wf w,

mum w Patented June 30, 1925.

UNITED STATES PATENT OFFICE.

'ROY- D. CONWAY, OF EAST ORANGE, NEVVJERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, F NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ALARM SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES.

Application led December 29, 1922. Serial No..609,571.

- for automatic telephone exchanges and is au -improvemi-rnt upon my invention disclosed in latcntNo. 1,491,337 of April 22, 1024, entitled Coin collect system for automatic telephone exchanges.

lts object istolg-i-ve an alarm at the central otl'icc, if ythe subscribers attempt to secure connections without depositing the required coms. .l

In the system of vsaid application, the

V deposit of a coin grounds one side of the line through the coin box magnet and an impulse of current is automatically applied lo the calling line to operate said magnet to cause it to collect or refund the coin and remove said rground when the calling party replaces his receiver. In said application, means is disclosed for operating an alarm signal at the exchange if the ground is not removed when the com box magnet operates and the operating impulse ceases, but no 'alarm is given if a ground is applied when f, down the connection.

the call fis/'initiated and removed before the calling party replaces his receiver to break Thus, a subscriber eould apply a ground in making a call and thus obtain control of the impulse circuit for `setting' the central office automatic switches, build up his connection, and after talking, but before replacing his receiver, could remove the ground and no alarm would be given on the replacement of the receiver and the restoration of the automatic central oliicc switches. f

It is the object of this invention to render it still more difficult to beat the coin boxes without detection, and this invention consists in a circuit arrangement whereby a test is made of the calling line when the coin collect circuit functions and if at that time the calling line circuit is not in the condition it would be if a coin had been dropped in the coin chute an alarm signal is given at an lattendants board at the exchange, as well as .if the calling line circuit is not restored to its normal condition, as it should be, by the operation of the coin box magnet and the cessation of its operating impulse.

Referring to the drawings, Fig. 1 shows a calling line, a primary line switch andthe coin control circuit; Fig. 2 shows a secondary line switch, a selector, a connector and kthe called line.

The' invention will be more readily understood from a detailed description of the operations involved in setting up a connection.

Upon the removal of the receiver at the calling substation, the relay 101 of the primary line switch PLS individual to the calling lineis operated over the calling line circuit. ln attracting its armature it closes a circuit including the pull down winding 102 ofthe line switch which causes theline switch to seize the preselected trunk by operating the set of springs in the well known manner, as shown. and particularly described, for example, in Patent No. 1,304,- 369. to A. J. Ray of May 20, 1919. The calling line is now extended to the trunk circuit, whereupon relay L is operated as follows: free pole of battery, contact 104 of relay Y, conductor 105, contact 106 of relay S, conductor 107, contact 103 of relay N N, resistance 187, conductors 109, 110, 128, the inner right armature and back contact of relay B, lower armature and back Contact of relay A., ringconductor 165,

coutacts

162 and 163 of the line switch,conductor 153, the telephonie loop at the calling substation, tip conductor 164, springs 100 and 10T of the line switch, lconductor 158, upper armature and back Contact of relay A. left armature and back contact of relay l, re-

Sil

tardation coil 188, relay L. outer left armature and back contact of relay N N to ground.

.ill

conductor 125, springs 112, 113, cutloft winding 100, secondary 197 of induction coil to tree pole ot' battery.

When the primary line switch PLS operated and closed springs 114 and 115, the following circuit was closed to operate the secondary line switch SLS to seize an idle first selector; grounded sp1-inf 115spring 114, secondary line switch holding conductor 116, outer left armature and back contact of relay Il H, conductor 117,

conductors

201 and 202, pull-down coil Q03 ot' the secondary line switch, contact 204, conductor 205, slow relay 206, to free pole of battery. The secondary line switch SLS in operating closes a locking circuit for itself, including its windings T and 203 in series, contact 208, to grounded holding conductor Q01.

Relay L, in attracting its left armature, operates slow-to-release relay N, which operates relay N N. Relay N N in attracting its` outer lett armature removes a short circuit from about the high resistance 11S t'or a purpose which will shortly appear, and in attracting its inner lc'l't armature grounds the release conductor 125 over conductor 140 to hold up the primary line switch PLS aiter relay L releases. Relay N N in attracting its inner right armature at 102i substitutes relay RT for resistance 18T in the calling line circuit. Relay RT is thus connected to the ring side 1525 o'll the alling line. Relay RT is marginal and will not operate over the line circuit in series with relay L and resistance 118. ResistA ance 11bl is normally short eircuited, its short circuit being removed when relay N N operates to increase the margin of operation of relay RT.

The circuit remains in this condition until the calling party inserts a coin in the coin box. The coin bosY may be of the type shown and described in Patent No. 1,013,219. to t). F, Forsberg, issued November '1012. As shown and described in detail in said patent, the deposited coin causes the closure ot contact 13 thus grounding the tip side ot the line 104, and since the receiver is now removed from its hook, this grouinl is also connected to the ring side of the line 152i. The application of this ground closes a shunt about relay L and the high resistance 118, whereupon the marginal relay RT operates over a circuit including the ring side of the line 153, the calling substation receiver hoolc, magnet .\1 to ground closed by contact 13 of the coin box.

Relay RT in operating, energizes relay S over the following circuit: battery, armature and front contact of relay RT, coudnctor 121, relay S', colnluctors 1;2, 12.". `outer left armature and front contact ot` relay N N to ground. In attractingr its outermost left armature, relay S connects conductor 116 to conductor 117 independently of the outer left armature and back contact of relay H H. In attracting its middle left armature, relay S', provides a direct path to ground through coil 188 from the tip side 164 of the line short circuiting relay L and resistance 118. Relay L releasing, opens the circuit of relay N which is slow to release. ln attracting its innermost left armature, relay S connects the impulse relay R to the ring side 153 of the line. In attracting its innermost right armature it removes rela RT from the calling line circuit and locks itself to bat` tery at a normal contact ot relay Y and to the grounded sleeve or release conductor 121. This conductor was groumled when the secondary line switch ser/.ed the lrst selector in the well known manner. The locking circuit of relay S is as tollows: free pole of battery, Contact 104 oi' relay Y, conductor 10.3, inner right armature aud front contact of relay S, relay S', conductor 12:3, to grounded sleeve wire 12+. Vln attracting its outermost right armature, it operates relay ll H and slow relay H. The circuit for relay H H leads over conductor 176 and the outer right armature of vrelay l?) and conductor 189. Relay H then locks itseltl over coinluctors 174, 176, outer right armature and back contact of rela-y B, conductor 189, to battery at its own armature and front contact. Relay H Il being connected to conductor 189 is also held up by the arma-ture of relay H.

Relay H ll in attracting its inner right. armature, connects grounded conductor ll-.s over conductor 11T to the release comluetor 125, leading back to the primary line switch to maintain the cut-oil1 winding 100 thereof energized iln'lependently of the ground supplied at the inner left armature oi relay N N, which relay releases when slow rclay N releases, the. circuit of relay N having been opened as relay L was short circuitcd when relay S operated. rlhe grounded conductor 14S is however extended to the sleeve conductor 125 by relay H ll before relay N, which` is slow to release, falls back.

The calling party now operates his sender in accordance with the first digit of the wanted number, and on the return ot the sender to its normal position, the following circuit including the impulse relay R is interrupted: battery, relay R', conductor 120. innermost left armature and t'ront contact ot' relay S', conductors 12T, 12S, inner right armature and back contact of relay l, lowcr contacts of relay A, the. ring side la?) ol' the line. the substation loop. the tip side 113-1- of the line. the upper back contacts oll relay left armature and hack contact ol relay ll. retardation coil 18h' to ground at thc middle lelt armature ot relay S'. The ground connected to thc tip side o1 the line at 121 does not interfere with this impulse circuit. Upon the initial operation of the impulse relay R before the sender was operated, it closed at its lower front contact a circuit t'or slow-to-pull-up relay D which in operating extended the trout contact of relay R to energize relay D D which connected the incoming and outgoing ends of the tip and ring conductors together, these conductors including a pair ot' condenser-s 129, 130. Upon the first retraction of the armature of impulse relay R, due to the sender interrupting the. line. relays D and D D instantly retract their armatures, the latter disconnecting the incoming tip and ring comluctors trom the outgoing tip and ring eoiuluctors.` Relay I) is constructed and arranged so that it will not again attract its armatures while the impulse relay armature is vibrating. Relay D D lthus remains inert during this period to maintain the condensers disconencted 'from the outgoing ends ot' the tip and ring conductors to preventI interference with the character ot' the impulses. by the discharge of the. o ondensers.

Only parts ot' the switches S and C are shown, since these-switches are well known. They may be of the type shown in Reissue Patent No. 13,901, issued April 13, 1915 to F. Newforth. Jr.

Assumingthat the selector S and preced ing switches have been set and the. calling line extended to the connector C, the impulse relay 210 (Fig. 2) ot theconnector C is operated over the following circuit: tree pole ot battery, right winding of relay 210, normal contact ot relay 211. conductor 23?), ring conductor 212. multiple terminal 213 and brush 21AL of the selector S, ring conductor 215, secondary line switch Contact 216,

ring conductors

232, 132, (Fig. 1) contact, 1321 ot relay J, conductor 1311, upper armature and front contact of relay R', Conductors 135 and 136, armature 137, conductor 138, polarized relay P, tip conductor 139, contact 140 of relay J, tip conductors 195 and Contact 226, tip conductor 227, brush 228, terminal 229 of selector S, tip conductor 230. conductor 231, normal contact of relay 211. left winding of relay 210 to ground. Relay 21() at its front Contact operates slow relay 210, which interposes a break in the circuit of release magnet 241 and grounds the sleeve wire 24:5 to hold the operated switches set. in the well known manner. I

The operations of setting the connector need not be described since they are well known and t'orm no part of this invention. .lhe impulse relay R', which is in circuit with the sender, at its upper armature and t'ront contact controls the circuit of the connector impulse relay 210.

lVlien the connection has been built up to the called line, the response of the called .down ot the connection.

party operates relay 211 which reverses the How of current in the tip and ring conductors leading back to the coin collect circuit. Relay l), which is polarized, thereupon operates. closing a. circuit for relay C to prepare a circuit including the coin collect source C C and the' falling line which circuit will be closed during the breaking The circuit for relay C is as follows: t'ree pole of battery, relay C and its normal upper contact, conductor 142, armature and alternate contact of relay P, conductors 192 and 15T, to the, grounded release wire 125. Relay C in attracting its armature locks itself to grounded sleeve wire 125. Relay J is also energized over the following circuit duer to the operation ot' relay l): t'ree pole ot battery, resistance 184, relay J, condultor lat), armature and normal contact ot relay K, conductor 142, alternate Contact and arma# ture ot' relay P, conductors 192 and '157, to grounded sleeve wirel 125. Relay J locks itself over its armature- 152, conductors 151, and 15T, to grounded sleeve wire 125. Relay J reverses the connections vot' the tip and

ring conductors

195 and 132 with the tip and

ring conductors

139 and 134, for a )urpose which will appear later. Relay (i in operating, closes the following circuit for relay A: tree pole of battery, relay A, conductor 151, uppermost armature and front contact of relay C, to the grounded sleeve conductor 124. Relay A extends the tip and

ring Conductors

158 and 165 leading from the primary line switch to the tip and

ring conductors

168 and 161 otl the trunk, cutting oft' the bridge. containing the im )ulse relay R and retardation coil 188. Relay R in releasing its upper armature rtanoves the bridge containingr the impedance coil 181 from across the talking conductors.

The subscribers may now converse. Talking current is fed t'rom the, connector to the calling line over the following circuit: free pole of battery, right whirling ot relay 210, outer armature and front. contact ot relay 211, (now operated) conductors 231, 23o, terminal 229, brush 228. conductor 22T, co-ntact 226,

conductors

225, 195, contact. 159 of relay J,

Conductors

131, 160 and 161, lower armature and front contact ot' relay A, Contact springs 162 and 1623. conductor 15:5, through the substation talking-set, conductor 161, springs lttt and 16T, upper armature and `front Contact ot` relay A. comluctor 16S, relay l?, com'luctors 139 and 179. armature 169 and front contact ot' relay J, conductor 132, conductor 2212, contact 21o. conductor 215, brush 2l-l-terininal 213.

comluetors

212 and 233, inner armature and frontrontact ot relay 211` left winding of relay 219 to ground. lurrent is fed to the called line over the windingsot relay 211.

lVhen the calling party replaces his reeeiver, relay 210 releases and ground is removed from the sleeve conductors i345, 23T, 235 and 124, hy the consequentl release ot slow relay 2li), which causes the. eonneetor and selectors to restore. The removal ot this ground also releases relay S', whirh in releasing its outermost lett armature releases` the secondary line switch SLS. Relay h" at.

v its outer right armature and haelt eontaet also closes a circuit l'or relay Y aa follows: tree pole ol hattery. outer right armature and haelt eontaet of relay S, conductor ITI` relay Y, contact 17:2 of said relay, eonductor 173. inner left armature and alternate contact of relay ll Il, lower eontaet ol'l the Constantly operatii'ifa interrupting maehine l to ground. Relay Il is still locked up. holding itseltl and relay H H operated and Consequently the primary line switch remains Relay Y in operating, loeks itself to grounded conductor IIN hy closingr its eonlar-t 177.

ll'hen the. interrupting machine l next closes its upper eontaet. a eireuit is closed to operate relay l hy way ol` the inner lett arn'iature and 'liront contact ol" relay Y. lelay l in attraetiinf its armatures impresses positive eurrent oll pre leralrly llt) volts from the eolleet source (l (l to the calling! line to operate. the polarized magnet lll ol the eoin hox at the. callingl station to collect the coin. 'l'his cirenil is as l'ollnwsi free pole. orlI souree C (l, resistance, lamp 5. conductor ITS. lower armature and front contact ot relay (l. now lor-lied to grounded sleeve wire 12T. relay Iflll` conductor ITD. lett arnuitnre and front. contact ot' relay B. upper armature and haelt eontaet of relay springs IGT and lll. tip eonduetor lol. polarized magnet )l contaet lil, to ground. Relay released when ground was removed t'rom the sleeve eonduetor 1Q-l at the connector. 'l`he polarized magnet. M operates to eolleet the eoin as; shown and deserihed in said Forsheu;r patent. In operating, magnet M lorlis itselt' to `ground hy closing Contact 11 and then releases tho eoin whieh opens eontaet Ill. Due, to the closure ot eontaet 1.1.. the magnet M remains operated as loir;T as the eoin current impulse lasts, as shown in Said l"orsl.el"' r patent. 'ln ease the lirst impulse. l'roni the interrupting machine 'l'ails to cause the eolleetion ol the coin. additional impulses are sent and the release, ot the primary line switeh PLS is held up in the` following' manner:

'hen the relay ll optniated. in attracting its outer right armature itv opened the loeltiner eireuit previously traeed I`or slow relay Il. hut at the same time a suhstitute cireuit is elosed at the malte-lxefore-hreal: contact of relay ll. hy way ot eol'iduetor 1l. to hattery at the right break contact ot' relay 'l`.

yThe relay 12)() operates in the eoin current circuit in series with the polarized magnet M and closes a circuit to operate and loci: re ay T. \Vitl1 rela 'l operated and locked1 the locking circuit tor relay Ilv is transferred to the armature and front eontaet oll ri-lav 19t). Relay ll as pointed out holds up relay ll'll which at its inner right armature 1s maintainingr ground on the sleeve eonduet-or leadings,r to the holding winding 11)() ot the, primary line switch. '.lhus these two alternate circuits maintain relay l-l operated until the ground at` the, suhstation is removed. As longl as relay Y remains operated, lamp ISU lights het'ore an at.- tendant..

Assuming, as in the normal ease, that the coin is eolleeted on the energization ol` magnet M hy thetirst impulse the second time the relay B operates vfrom the interrnpter l no ground will he present. at the suhstaton and the relay '19() will tail to operate and C the substitute eireuit for relay Il at the l'ront` eontaet ot' relay 15)() will not he present. telay ll aeeordingly releases. re-l leasingl relay ll ll. Relay ll ll in retraelink; its inner right armature remoyes ground trom the, sleeve eonduetor Il leadingl to the holding' winding lll() olE the line switch. resulting' in the release of the same.

ln ease the ealled party did not respond. polarized relay l) would not have shifted its armature and relay C would have reA mained inert.. .\t itsI lower armature. this relay would have conneeted negative i urrent trom the l1() rolt coin return source tlt through resistance lamp 8 to the calling' liml to canse the polarized magnet M to ret'nnd the eoin, loi-k up to zground at 1; aml open eontaet 12",. When the operatingcurrent is remoyed by the release, of relay Il. and maa` net M releasesl opening Contact: I2. the primary line switch releases'as deserihed.

Certain lines Called free lines are sagregated upon connectors which do noty reyersey the current tlow in the ealling line when the called party responds. ()n sueh calls. hattery is ted to the ealling` line over the impulse circuiti previously traced. the relay lt being halaneed hy the retardatiim coil IHS. the eondeusers 12). 13() separating the calling and called ends of the eireuit..

The retardation eoil VIRI is provided in these calls to prevent, short eireuitingg theA yoiee currents.

llpon diseonneetion in thisl class ol' calls, inasmuch as relay C is not operated` the coin is refunded as in the ease ol unsiueessl'nl calls.

Resistanee 192 is eonl'leeted to f rronnd at one end and to the. eondensers Il and lill) at the other end over normal contacts olI relay l) l). The other terminalsI ol' these condenserev are eonneeted over normal eontaets lOl) l In

llt

ot relay A to the armatures ot' relay l over which the relatively high potential coin eurrent flows. 'llnS arrangement is 4lor pre- `cha-nge from holding the switches set. by

holding relay 210 operated. relay J, which operates due to relay 211 operating, is provided to prevent the switches from remaining set after the parties replace their rcceivers.

-More particularly, when the calling party restores his receiver, and the called party still has his oft' the hook, inasmuch as relay l is held up from ground onv the sleeve wire 125, the circuit through the right winding of relay 210 and the coin ground is open at the switchhook of the calling line and thus the holding up of relay 210 to prevent the release of the switches, is avoided. Relay 210 therefore'releases, opening the circuit of the usual slow relay 240. The'release of `thc slow relay energizes the release magnet 211 which releases the connector and the release. of the slow relay removes ground from the sleeve conductor 235, which releases the selectors. The selectors release before the coin collecting operations are completed and inasmuch as the ground on the release wire 125, to which relay J is locked, cannot bc removed until these operations are completed the circuit referred to from the ground in the coin box to the right winding of relay 210 cannot be established.

When the called party restores first. relay 211 releases and reverses thel current flow in the calling line. In this event relays .l and K cooperate to prevent this condition from holding up the release of the switches. lhen the relay .l operated upon the response of the called party` it. reversed the current thus causing relay P to restore. It also closes at its armature 183 a circuit for relay K, this circuit including the conductors 151 and 157, and the grounded sleeve wire 125. Relay K is designed to be. slowto-pull-up, so that relay P will release before relay K operates to partly prepare a circuit to shunt relay J. `When the called party replaces his receiver and reverses the current fiow in the calling line, relay rP operates and shunts out relay J over resistance 184, conductor 185, armature and front contact of relay K, contact vof relay P, conductors 192 and 157, to grounded sleeve. wire 125. Relay J restores the original connections to the tip and ring conductors so that the ground in the coin box is now connected to the tip side 164 of the line to which the grounded side of relay 210 is connected.

'l`hus, when the calling party lsubsequently restores his receiver, no circuit could he maintained closed `from the coin ground to the winding ol relay 2l() to which the free pole of battery is connected. 'lhus` release is not prevented. Relay 1 is located in the tip side of the line rather than the ring side so that if. the called party hangs up immediately after the calling party and releases relay 211 `thus reversingT battery to the calling party before the slow relay in the connector has time to release and remove the ground from the sleeve wire which is holding up relay S', relay P will be operated when relay 211 releases over a circuit from the free pole of battery through right winding of relay 21() to thc coin ground, thusl short-circuiting relay J as described, which reconnects the coin ground to the left winding of relay 210 and reconnects the right winding of relay 210, which is connected to the free pole of battery, to the ring side of the .line which is open at the calling line switchhook. Thus release is not interfered with.

Certain levels of the selector S or a preceding selector may contain trunks leading to operators positions, such as information or toll operators. The induction coil 10 is provided to give such operators atone to inform them of the. character of the line. As shown in British Patent No. 15,133 of 1911, to Derriman, tone may be induced in the secondary winding 197 of the induction coil 10 froma. class tone source CT which is transmitted by coil 186 to the

sleeve Wires

124, 235 and 237, and thence to the operators head set, asshown and described in said patent.

If the calling party instead of dropping a coin, removes the receiver and fraudulently grounds the line in some manner, the. impulse relay R is placed under control of the dial as previously described. The calling party then sets the switches by means of the dial and establishes a connection with the called line. Before replacing his receiver, however, the calling party in order to revent lighting lamp alarm 180 as described, removes said ground. The replacement of the receiver restores the calling line to its normal condition, and causes the coin collect circuit of F ig. 1 to function as described up to the point Where relay B connects the collect source C C through relay 190 to the calling line. In the normal operation of the system relay 190 operates at this time and at its armature connects battery to relay T, which operates over an obvious circuit to ground at the sleeveI wire 125` Relay T in attracting its right hand armature rcmoves battery from conductor 4 and in attracting its left armature locks to grounded conductor 125. Since we have assumed the ground to have been removed before the replacement of the receiver, relay 190 does not operate and lock up relay T as described so that when relay B is operated by the lirst impulse from interrupter I and attracts its outer right armature, the continuity' contact controlled by said arn'iature substitutes batery on conductor 4 from the normal right hand contact of relay T for the battery from the alternate contact of relay H to hold slow relay H operated to prevent theA release ot the primary line switch. The circuit Jfor holding relay H operated is as Jfollows: ground, relay H, conductor 174, continuity contact of relay B, conductor 4, to battery at the right hand normal contact of relay T, now inert due to relay 190 not having operated. ihen interrupter l again releases rclay l, the outer right armature again applies battery to relay H before the battery connection described from the normal contact of relay T is opened by the opening of the continuity contact. It will be remenn bered that relay Y operated on the release of relay S and the closure of the lower contact of interrupter I, and at its outer lett armature locked itself to ground over the inner right armature of relay H H and conduetor 148. Relay Y at its right armature lights lamp 180. This lamp is located so as to be visible to an attendant who will know by its sustained illuminated condition that either the apparatus .is not functioning properly due to trouble or that someone is trying to beat the coin box. Since thel calling line is under these conditions held extended to the primary line switch, its number may be readily determined, and the matter investigated.

that is claimed is:

l, l'n a telephone system. a calling line having a sender and a coin controlled mechi anism, an automatic numerical switch` an impulse circuit for setting said switch, means for automatically extending the calling line to said switch, means operated by the deposit of a coin 'for altering the calling line circuit, a test relay responsive to said alteration for placing said impulse circuit under contro-l ot' said sender` means Vfor applying current to said linel to actuate said mechanism to dispose of the coin` an alarm signal` and means responsive to the normal condition of the calling line circuit to actuate said signal.

2. ln a telephone system. a culling line having avsender and a coin controlled mechanism, an automatic numerical switch, au impulse circuit for setting said switch, means for automatically extending the calling line to said switch, means operated by the `deposit of a coin for altering the calling line circuit, a test relay responsiveI to said alteration for placing said impulse circuit under control of said sender, means for masses applying current to said line to actuate said mechanism to dispose of the coin` a lamp,

and means thereafter responsive .to the normal condition ot' the calling line circuit. for continuously lighting said lamp.

3. In a telephone system, a calling line having a sender and a coin controlled mechk anisml` an automatic numeri al switch. au impulse circuit Jor setting said switch, a, non-numerical switch for extending the calling rline to said numerical switch, means operated by the deposit of a, coin for altering the calling line circuit, a test relay responsive to said alteration for placing said impulse circuit under control ot" said sender, means t'or applying current to said line to actuate said mechanism to dispose ol they coin` an alarm signal. and means responsive to the normal condition of theI calling line circuit to actuate said signal and hold said non-nmnerical switch in its operated position when said current is applied to the calling line.

4. ln a telephone system. a calling line having a sender and coin collect mechanism, an automatic numerical switch` an impulse circuit tor setting said switch. means Jfor automatically extending the calling line. to said switch, means operated by the deposit of a coin for grounding the calling line` a test. relay responsive to said ground for placing said impulse cir `.uit under control of said sender, means for applying current to said line to actuate said mechanism to dispose of the coin, an alarm signal, and means responsive to thc normal condition ot the calling line circuit to actuate said signal when said current is applied to the calling line.

5. ln a telephone system, a calling lim` having a sender and a coin controlled mechanism, an automatic numerical switch` an impulse circ-uit lfor setting said switch, means 'for automatically extending the. calling line to said switch, means operated by the deposit of a coin in said mechanism t'or grounding the calling line, a test relay responsive to said ground for placing said impulse circuit under control ot said sender. means for actuating said mechanism to dispose of the, coin, means in said coin controlled mechanism tor thereafter removing said ground from the line, an alarm signaL means to actuate said signal` and means responsive to the coin controlled ground and the removal thercotl for restoring said signal.

(i. YIn a telephone system, a calling line comprising a sender and a coin controlled meelnmism; an automatic numerical switch; an impulse circuit for setting said switch; means for automatically extending thc`calling line to Said switch; means actuated by the deposit of a coin for grounding one side of the line via the coin mechanism: a test relay responsive thereto for placing said impulse circuit under control of said sender; a grounded source of current; means for connecting said source to the line to actuate said mechanism to dispose of the coin; an alarm signal; and means, responsive when said Source of current is connected to the calling line in the absence of a coin, for actuating said alarm signal.

7. Ina telephone system; a calling line; a senderand a coin controlled magnet; an automatic numerical switch; an impulse circuit for setting said switch; means for automatically extending a calling line to said switch; means, actuated by the deposit of a coin, for connecting the coin magnet from one side of the line to ground; a test relay responsive thereto tor placing said impulse circuit under control of said sender; a

grounded source of current at the central oflice; means for connecting said source to lsaid line to actuate said magnet to dispose of the coin; means for disconnecting said source from said line to remove the ground therefrom by restoring said magnet; an alarm signal; and means, responsive to the improper application to, or removal of ground from, said line, to actuate said signal.

8. In a telephone system, a calling line, a sender and a coin'controlled magnet, an automatic numerical switch, an impulse circuit -tor setting-said switch, means for auto'- matically extending a calling line to said switch, means actuated by the deposit ot a coin for connecting the coin magnet from one side of the lineto ground, a test relay responsive to the grounding of the line for placing said impulse circuit under control of said sender, a grounded source of current at the central otce, means responsive to the replacing of the receiver of the callin line for connecting said source to the line w crcby said magnet is operated to dispose of the coin, an alarm signal, and means responsive to the improper removal of ground from said line to actuate said signal when said current source is connected to the calling line.

9. In a telephone system; a calling line; a sender and a coin controlled magnet; an automatic numerical switch; an impulse circuit tor setting said switch; means for automatically extending a calling line to said switch; means actuated by the deposit of a coin for connecting. the coin magnet from one side of the line to ground; a test relay responsive to the grounding of the line for placing said impulse circuit under control of saidsender; a grounded source of current at the central otlice; means responsive to the replacing of the receiver of the calling line for alternately connecting said source to, and disconnecting said source from, the calling line; an alarm signal; means for actuating-said signal until the current source is no longer connected to the calling line; a circuit including said current source and magnet for operating the magnet'to dispose ol the coin; and means effective after the coin has been disposed of, for completely disasseciating the source of current from the calling line.

l0. In a telephone system, a calling line, a sender'and a coin controlled magnet associated therewith, an automatic numerical switch, an impulse circuit for setting said switch, means for automatically extending the calling line to said switch, means actu-` ated by the deposit of a coin for altering the calling line circuit, a test relay at the central ofiice responsive to the circuit alteration for placing said impulse circuit under control of said sender, a source ot current for operating said coin controlled magnet, means responsive to the opening of the'calling line circuit for connecting said source of current to the calling line, an alarm signal at the central oiiice, and means responsive to the normal condition of the calling line for actuating said signal when said current source is applied thereto.

ll. In a telephone system, a calling line including a sendery and a coin operated mechanism, means in said mechanism re sponsive to the deposit of a coin. for grounding the calling line, an automatic switch, a circuit controlled by said sender for setting said switch, means responsive to thegrounding of the calling linek for completing said switch setting circuit, a source of current supply, means for connecting said current source to the calling line to operate said mechanism to dispose of a coin, an alarm signal, and means responsive Whenever a coin is not disposed of for actuating said signal.

12. In a telephone syst-em, a calling 4line including a sender and a coin operated mechanism, means in said mechamsm responsive to the deposit of a coin for grounding the calling line, an automatic switch, a called line, a circuit controlled by Said sender for setting said' switch to build up a connection to the called line, means responsive to the grounding of the calling line for completing said switch setting circuit, means responsive to the partial breaking down of the connection to operate said mechanism to dispose of the coin` an alarm signal, means for preventing the complete breaking down of the connection unless a. coin is disposed of, and means responsive during the breaking down of the connection to actuate said Signal. l y

18. In a telephone system, a calling line including a sender and a coin operated mechanism, means in said mechanism responsive to the deposit of a coin for grounding the calling line, an automatic switch, a called line, a circuit controlled by said lli() sender for setting said switch to build up a connection to the called line, means responsive to the grounding of the calling line for completing said switch setting circuit, means responsive to the partial breaking down of the connection to operate said mechanism to dispose of the coin and to restore said mechanism to normal, an alarm signal, means responsive to the breaking down of the connect-ion for actuating said signal, and means for preventing the total breaking down of the connection unless the coin mechanism {irstoperates to dispose of the coin.

14. In a telephone system; a calling line including a sender and a coin operated mechanism; means in said mechanism responsive to the deposit of a coin for grounding the calling line; an automatic switch; a called line; a circuit controlled by said sender for setting said switch t0 build up a connection to the called line; means responsive to the grounding of the calling line for con'ipleting said switch setting circuit; means responsive to the replacing of the receiver' at the calling station for initiating the breaking down of the connection; a source of current supply; a circuit including the calling line, the coin operated mechanism and the current source; a device operable to close the circuit aforesaid by connecting the current source to the calling line; an alarm signal; means, operated while the breaking down of the connection is in progress, for' actuating said signal, and for intermittently operating said circuit closing device; means in said coin operated mechanism for disposing of the coinv the first time said circuit is closed; means in said coin operated mechanism for removing the ground from the Calling line the first time said circuit is opened providing the coin has been disposed of; and means for retaining the connection with the calling line and for continuing to actuate said signal providing a coin has not been disposed of by said coinl controlled mechanism.

In witness whereof, I hereunto subscribe my name this 28th day of December A. D., 1922.

nor D. CONWAY.