US2427000A

US2427000A - Coin-operated telephone system

Info

Publication number: US2427000A
Application number: US456482A
Authority: US
Inventors: Hovland Henry
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1942-08-28
Filing date: 1942-08-28
Publication date: 1947-09-09
Anticipated expiration: 1964-09-09

Description

p 1947 H. HOVLAND COIN OPERATED TELEPHONE SYSTEM Filed Aug. 28, 1942 6 Sheets-Sheet M/VE/VTOR H. HOVLAND ATTORNEY Sept. 9, 1947.,

H. HOVLAND COIN OPERATED TELEPHONE SYSTEM Filed Aug. 28, 1942 6 Sheets-Sheet 2 Sept. 9, 1947. H; HOVLAND 2,427,000

COIN OPERATED TELEPHONE SYSTEM F iled Aug. 28, 1942 6 Sheets-Sheet 3 H. HOI/LAIVD ATTORNEY wssk kabtk n wt S p 1947. H. HOVLAND com OPERATED TELEPHONE SYSTEM Filed Aug. 28, 1942 a Sheets-Sheei 4 SUD L823 m2 50% 3; 5.3 6. 2:3

lNl/ENTOP H. HOVLAND ATTORNEY Sept 9, 1947. HOVLAND COIN OPERATED TELEPHONE SYSTEM Filed Aug. 28, 1942 6 Sheets-Sheet 5 lNl/E/VTUR [F- H HOVLA/VD ATTORNEV '2 v i m 1?. q A

INVENTOR HHOVLA/VD Sept. 9, 1947. H. HdVLAND 2,427,000

COIN OPERATED TELEPHONE SYSTEM Filed Aug. 28, 1942 e Sheets-Sheet e 7 ATTORNEY Patented Sept. 9, 1947 COIN-OPERATED TELEPHONE SYSTEM Henry Hovland, Williston Park, N. Y., assignor. to

Bell Telephone Laboratories, Incorporated New York, N. Y., a corporation of New York Application August 28, 1942, Serial No. 456,482

6 Claims.

This invention relates to telephone systems and particularly to systems comprising coin stations and arranged for overtime charging:

Objects of the invention are the improvement of systems. comprising coin stations and particularly the improvement of means for collecting and refunding coins and an increase in the efiiciency of the timing means provided for overtime charging.

It is known in automatic telephone systems comprising stations of the prepay coin type to provide a coin control trunk circuit associated with a first selector for controllin the collection and refund of coins. It is also known to provide timing means for timing the interval for which coins .have been deposited. According to this invention, the timing means associated with a coin control trunk circuit and first selector in an automatic telephone system comprising prepay coin stations is rendered inoperative in case the selector i operated to select a trunk t an operator.

The invention and its features will be better understood by considering a, system in which the invention is embodied, one such system being shown in the drawing which forms a part of this specification. The invention is, however, not

limited in its application to the specific system shown but is generally applicable to systems comprising. coin stations arranged for overtime charging.

Referring to the drawing:

Fig. 1 shows a coin subscribers station A and line Li, a line finder LFI and a coin trunk circuit CT;

Fig. 2 shows a timing circuit TC individual to the trunk circuit CT of Fig, 1. Fig. 2 further shows a first selector SI associated with the trunk circuit CT, a connector Cl, a line L2 and a called subscribers station B;

Fig. 3 shows a trunk finder TFI having access to coin trunks including trunk CT, for connecting a coin trunk to a monitoring operator;

Figs. 4 and 5 show a coin collect and monitor circuit CCM terminating at an operators position;

Fig. 6 shows a recording completing trunk circuit accessible to selectors including the selector SI; and

Fig. 7 shows the relative position in which Figs. 1 to 6- inclusive are to be placed to form an operative arrangement.

The invention is illustrated in an automatic telephone system in. which switches of the stepby-step type are used for extending connections between calling and called subscribers lines. Reference may be had topages 53 to 65 0f the sec- 0nd, edition of Automatic Telephony" by Smith and Campbell for a. description of the structure and operation of step-by-step selector and connector switches; and reference may be had to the patent to R. L. Stokely No. 1,799,654 granted April 7, 1931, for a description of a, line-finder switch of the step-by-step type.

The subscribers stations A and B are of; the type usually provided automatic telephone systems, the station A being further provided with a coin control mechanism comprising the coin actuated contact 6' and. the coin collect and refund magnet 1. Reference may be had to the patent to O. F. Forsberg No. 1,043,219 of November 5,. 1912, for a description of a prepay coin box. The timing camsof timing circuit TC may be part of a timer mechanism such as is: disclosed in the patent to E. D. Mead No. 2,112,375 granted March 29, 1938.

Further description of the system shown in the drawing Will be facilitated by a description of the operations involved on calls initiated at, station A. Assume first, a call from station A to station B. When the receiver at station A is removed from normal position, a line finder LFI is operated, in the manner described in the aforementioned patent to R. L. Stokely, to connect the line Ll to a coin trunk CT. Upon connection of line Ll through the brushes of line-finder switch LFlto coin trunk CT, relay 20 is operated in a circuit traced from ground at the inner lower back contact of relay 21, winding of relay 20, winding of V retard coil It], a back contact of relay i6, upper back contacts of relay I 4', conductor ll, upper brush of line finder LFI, upper conductor of line Ll, lower normally closed contacts of the dial 8 at station A, through transmitter 9,, left-hand contact of the receiver-hook switch, left winding of induction coil Ill, lower conductor of line Li, middle brush of line finder LFl, conductor 12, lower back contacts of relay l4, inner lower back contact of relay l6, outer lower back contact of relay 2T, inner upper back contact of relay 3-5 to battery at the lower back contact of relay 26. The operation of relay 2!! closes circuits for

operating relays

24 and 29. The circuit for operating relay 24 is traced from ground at. the front contact of relay 20, through the winding of relay 24 and outer upper back contact of relay 35. The circuit for operatin relay 29 is traced from ground at the front contact of relay 20, through the inner upper back contact of relay 21, back contact of relay 3.2, winding of relay 29 and the upper back contact of relay 34, The operation of relay 29 opens the short circuit across retard coil 30 and connects ground to conductor l3 to hold line finder LFI. The operation of relay 24 closes a circuit for operating relay 21, this circuit :being traced from ground at the front contact of relay 24, through the winding Of relay 2'! and outer upper back contact of relay 35. The operation of relay 2'! closes a holding circuit for relay 23, independent of relay 28; changes the circuit through the winding of relay 20 to include the resistor 25 and the winding of relay 3|; and closes a bridge across conductors 5| and 52 to operate the line relay (not shown) of selector SI. Relay 28 is held operated in series with resistor 25; but relay 3| is marginal and does not operate until a coin is deposited at the calling station. The bridge across conductors 5| and 52 is traced from conductor 5| through the uppermost back contact of relay 39, winding of relay 38, retard coil 30, winding of retard coil 30, lowermost back contact of relay 44, resistance 46, uppermost front contact of relay 21, winding of relay 31, lowermost back contact of relay 39, to conductor 52. Relays 31 and 38 are polarized relays, the current through the operating windings of these relays being in the operating direction for relay 3'! and in the nonoperating direction for relay 38. The operation of the line relay of selector SI effects the connection of ground to the holding conductor 53 in usual manner, this ground potential bein further connected through the lowermost back contact of relay 35, to conductor |3 in parallel with the ground from the front contact of relay 29.

When the coin is deposited by the calling subscriber, the coin contacts 6 are actuated, connecting ground through the winding of coin magnet l' to the upper conductor of line Ll, thereby increasing the current through the winding of relay 3| to effect its operation. The operation of relay 3| closes a circuit through the winding of relay 26, lower back contact of relay 35 and conductor I3, to ground at the front contact of relay 29. Relay 26 operates; and it looks independent of relay 3|, through the back contact of relay 35 to ground on sleeve conductor |3. Relay 28 also locks directly to ground on conductor 53 if the selector SI has already connected holding ground potential to this conductor. The operation of relay 26 opens the circuit through the winding of relay 3| and connects the winding of relay 33 to the lower conductor of line Ll, thereby causing the release of relay 3| and the operation of relay 33. Relay 33 closes a circuit for operating relay 32 and at its lower front contact closes the bridge across conductors 5| and 52 independent of the contacts of relay 21, At its middle upper front contact relay 26 closes circuits for operating relays 35 and 36, the circuit for operating rela 35 being traced through the upper back contact of relay l5. Relay 35 looks under the control of relay l6, but independent of relay 2B; and closes a circuit for holding relay 35 operated. The operation of relay 35 causes the release of relays 24 and 21, disconnects sleeve-conductor 53 from sleeve conductor I3, and connects ground to sleeve conductor l3. The release of relay 2! short-circuits resistor 25; and the release of relay 24 short-circuits the winding of relay 20, thereby causing the release of relay 20. Since relays 24 and 21 are slow in releasing, relay 33 is fully operated before relay 2! releases, due either to the operation of rela 35 or due to the release of relay 20 in case this relay releases upon deposit of a coin, to maintain the bridge across conductor 5 a d 52. The operation of relay 32 closes a circuit for holding relay 29 operated, independent of relay 2!.

With relays 25 and 23 operated and relay 21 released, conductors H and H are connected through talking condensers |5 to conductors 5| and 52 of selector S so that dial tone is transmitted from selector SI to the calling station. When the subscriber dials the first digit of the called subscribers number, relay 33 is alternately released and reoperated, due to the opening of the subscribers loop at the impulse contact of the dial 8, as many times as there are units in the digit dialed. The first release of relay 33 causes the release of relay 32; and, being slow in operating, relay 32 remains normal during the receipt of the remaining impulses of the digit. Each release of relay 33 opens th bridge across conductors 5| and 52 thereby repeating the impulses, corresponding to the first digit dialed, to the first selector Si. The release of relay 32 causes the release of relay 29 whereby the retard coil 30 is short-circuited to improve the transmission of impulses to the selector S l. The release of relay 29 also disconnects the talking condensers |5 from conductors 5| and 52. The selector SI is operated in response to the dial impulses to select a level corresponding to the first digit dialed and to select the first set of terminals in that level which is connected to an idle trunk or succeeding switch. Assuming the selected set of terminals to be the terminals 75, the line relay of connecter C| is operated. Relay 85 closes a circuit for operating relay 85; and relay 86 connects holding ground potential through conductor 83 and brush 13 to conductor 53. The next two digits dialed by the calling subscribed are re peated by relay 33 of coin trunk circuit CT to the line relay 85 of connector CI. The connector Cl is thereby operated in usual manner to select the terminals of the called line, to make a busy test of this line, and to connect a ringing current source to the line in case the line is idle.

If the call is answered by the called subscriber, a circuit is closed for operating relay 84; whereby the connections between the conductors 8| and 82 and the windings of relay 85 are interchanged so as to reverse the current through conductors 5| and 52 and thereby cause the operation of polarized relay 38 and the release of polarized relay 3'11. With relay 38 operated and relay 31 released. a circuit is closed for operating rela 39, this circuit being traced from battery through resistor 4|, winding of relay 39, the inner lower back contact of relay 48, outer back contact of relay'43, back contact of relay 31, front contact of relay 38, ground potential on conductor 53. Relay 39 looks to conductor 53 and closes a circuit for operating relays 43 and 44, this circuit being traced from battery at the inner upper back contact of relay 55 of timing circuit TC, through conductor 54, winding and continuity back contact of relay 44, all in parallel with the circuit path from battery through the winding of relay 43, thence through the inner lower front contacts of relay 39, to ground on conductor 53. The operation of relay 33 short-circuits the winding of relay 38 and interchanges the connections between conductors 5| and 52 and the windings of relays 31 and 38 thereby reversing the current through the winding of relay 31, causing the reoperation of relay 3'! and the release of relay 38. When the slow-to-operate relay 43 operates, it closes a circuit including a back contact of relay 38 for operating relay 4!). Relay 40 looks directly 5 to. the ground on conductor 53, independent of relay 38. The operation ofrelay 40 opens the short-circuit across the winding of relay 38; but relay 38 does not reoperate since the current through its windingis in the non-operating direction. The operation of relay 44 closes a lookin circuit to ground at the outer'lower'front contact of relay 35, opens the impulse repeating bridge through resistor ls across conductors 5| and 52, closes a circuit for operating relay I4, and connects ground to conductor '97 to start the operation of thetiming circuit TC. Rela I I connects the calling subscribers line, through conductors II and I2 and the inner front contacts of relay- I4, directly to the windings of relays 38 and 31 thereby holding relay 85 operated and completing the talking connection, through the talking condensers of connector C'I, between the line LI and the line L2.

When ground is connected to conductor 91 due to the operation of relay M upon answer of the called subscriber, the start relay 5! of the timing circuit TC is operated thereby closing a circuit for operating'the rotary magnet 58 of the timer mechanism to start the timer cams BI and 62 in operation. Relay 5? also closes a locking .circuit independent of the normally closed contacts of timer cam 6!, these contacts being opened as soon as the timing elements move out of normal position. At the end of an interval of four and a half minutes after the operation of cams SI and 62 i initiated, cam 62 actuates its associated contacts, thereby closing a circuit including the outer lower back contact of relay 65 for operating relay 64. Relay 64 connects ground through its inner upper front contact and the inner lower back contact of relay 65 to conductor 99 to operate the group relay I associated with the group of coin trunk circuits which are connected to one level of the bank of the trunk finder TFI. Relay I00 connects ground to the associated commutator segment of each of the trunk finders having access to the trunk circuit CT and connectsground to start conductor ST to start an idle trunk finder, in well-known manner. Assuming the trunk TFI to be the first idle finder in the group, the connection of ground to conductor ST cause the operation of relay I2I. Relay I2I closes a circuit from battery at the outer lower back contact of relay I24, through the lower winding of stepping relay I23, back contact of rotary stepping magnet H6, and back contact of vertical steppin magnet I I5, to ground at the inner upper front contact of relay I2I. Relay I23 operates thereby closing a circuit for operating the vertical stepping magnet H5. This circuit is traced from battery at the outer lower back contact of relay I24, winding of vertical stepping magnet H5, lower back contactof relay III, and front contact of relay I23 to ground at the inner upper front contact of relay I2=I. The operation of magnet II steps the two sets of brushes. I IlI'to I84 inclusive and I 35-to-I08 inclusive, up to the first level of the associated terminal banks and opens the operating circuit of relay I23. If the trunk circuit CT is not connected to a set of terminals in the first level, relay 123 releases when stepping magnet H5 operates thereby causing the release of magnet I I5. In this case the release of stepping magnet II5 again closes the circuit through the lower winding of stepping relay I23, thereby causing the reoperation of relay I23; and the vertical stepping magnet II 5 is again energized to step the brushes up to the next level of the terminal banks. Thus the stepping relay I23 and. vertical stepping magnet H5 cooperate to step'the brushes to the-level inwhich the trunk. CT is ter minated. Assuming the trunk CT to be connected to the terminals of the first level of the bank of the trunk finder 'I'FI, the stepping relay I23 is held operated, when the brushes are stepped up to the first level, in a circuit which is traced from battery through the outer lower back contact of relay I24, lower winding of relay I23, back contact of rotary stepping magnet H6, upper winding of relay I I7, commutator brush H3 and theengaged first segment of the commutator, to ground at the upper front contact of the group relay I30. Relay I23 is thus held operated and relay II I is-energized sufiiciently by the current through its upper winding to close its inner lower front contact and thereby energize its lower winding in series with the winding of the vertical stepping magnet H5. The stepping magnet II5 is not operatively energized-in this circuit. Relay III is slow in operating to delay the first rotary step to prevent snagging of the brushes due to vibration. The operation of relay II'I transfers the stepping circuit from thevertical to the rotary magnet, the rotarymagnet being energized in a circuit traced from battery through its winding, the outer front contact of'relay I ll, front contact of relay I23 toground at the inner upper .front contact of relay I2I. The-operation of rotary stepping magnet H6 .advances the brushes into engagement with the first set of terminals in the selected level and opens the circuit throughthe lower winding of relay I23 to cause the release of thi relay; The release of. the stepping relay I23 causes the release of the rotary stepping magnet H6 thereby again closing'the circuit for energizing the lower winding of 'relay I23. Relay I23 and rotary stepping magnet H5 thus cooperate'to advance the brushes, .step-by-step, until the brushes engage the "terminals to which the coin trunk circuit CT is connected; whereupon a circuit is closed from ground at the outer upper front contact of relay I2I; upper winding of relay I23, upper backcontact of relay I24, resistor H9, upper winding of relay I09, brush I63 of'trunk finder TFI, conductor 93, through the inner lower front contact of relay-64 and winding of cut-off relay 65 of'timing circuit TO, to battery. Relay I23 is held operated by the current in this circuit so as to hold the rotary magnet II6 energized to prevent further stepping. Relay I09 is sufficiently energized by the current through its upper winding to close I its inner lower front contact, thereby energizing its lower winding to complete the actuation of The circuit for energizing all of its contacts. the lower winding of relay I09 includes the front contact of the rotary stepping magnet I I6 and the front contact of relay'l23. The complete operation of relay I69 closes a short circuit across resistor H9 to cause the operation of the margina'l cut-oif relay 65 of timing circuit TC, closes a holding circuit for relay 64, closes a circuit for operating relay I'BI of coin collect and monitor circuit CCM, and closes a circuit for operating relay I26. Relay 65 looks to conductor 93 independent of relay 64, opens the operating circuit of relay M, and disconnects round from conductorIII-i so as to release group relay I03 if no other coin trunk, which is connected to the same level, is then awaiting connection to a coin collect and monitor circuit. relay 56 1 includes the locking contact of relay 64,

- 7 conductor Mytrunk finder brush I34, a front.

The circuit for holding contact of relay I09, conductor I 34, to ground at aback contact of relay I64 of the coin collect and monitor circuit COM. The circuit for operating relay I6I includes a back contact of relay I60, conductor I43, a front contact of relay I09, trunk finder brush I01, conductor 91, and a front contact of relay 44 of coin trunk CT, to ground potential on conductor 53. After relay 65 operates; conductor 91 is connected through a front contact of relay 65 to conductor 53, whereby relay- I4 of coin trunk CT and relay I6I of coin collect and monitor circuit CCM are held operated independent of relay 44 under the control of relay 65. The aforementioned circuit for operating relay I24 is traced from battery through the upper winding of relay I24, lowermost front contact of relay I09, to ground at the upper front contact of the vertical off-normal springs III, these springs being actuated as soon as the shaft of the trunk finder moves out of its normal position. The operation of relay I24 causes the release of relays I2I, I23 and I I1 and the release of rotary stepping magnet H6, and transfers the start conductor ST from the trunk finder TFI to'the next trunk finder in the group in usual and well-known manner. With relay I24 operated, relay I09 is'locked through its inner lower front contact, inner upper front contact of relay I24, conductor I46, to ground at a front contact of relay I6I in the coin collect and monitor circuit COM. The ground at the lower front contact of relay I6I is also connected through a back contact of relay I60, conductor I45, outer upper front contact of relay I24, inner upper front contact of relay I09, trunk finder brush I03 to conductor 93 to hold cut-01f relay 65 of timing circuit TC. Relay I2I is slow in releasing so that conductor I45 is connected to ground at the outer upper front contact of relay I2l until after ground i connected to thi conductor by the operation of relay I6! of coin collect and monitor circuit COM. The aforementioned operation of relay 65 of timing circuit TC opens the direct connection between conductors I and 52 and conductors 61 and 68 so that the talking connection between the calling and the called subscribers lines includes the talking conductors of trunk finder TFI and coin collect and monitor circuit CCM. The operation of relay 65 connects ground at the lowermost front contact of relay 64, through the lowermost front contact of relay 65, to conductor 53 to maintain ground on this conductor to prevent release of the connection until the coin collect and monitor circuit has collected the coin. The operation of relay 65 also disconnects battery from conductor 54, thereby causing the release of relay 44 of the coin trunk circuit. Relay I65 of the coin collect and monitor circuit CCM is operated in series with the calling line, this circuit being traced from bat tery through the lower winding of relay 85 of connector CI, the upper front contact of relay 84, conductor 8I, brush ll of selector SI, conductor 61, conductor 95, brush I05 of trunk finder TFI, a front contact of relay I09, conductor I4I, lowermost back contact of'relay I85, inner lower back contact of relay I55, conductor I3I, a front contact of relay I09, brush IOI of trunk finder TFI, conductor 9I, conductor 5|, the uppermost front contact of relay 39, winding of relay 31, lower front contact of relay I4, conductor I2, middle brush of line finder LFI, lower conductor of line LI, through the telephone at station A, back over the upper conductor of line LI, upper brush of line finder LFI, conductor II, upper front contact of relay I4, winding of relay 30, lowermost front contact of relay 39, conductor 52, conductor 92, brush I02 of trunk finder TFI,-a front contact of relay I 09, conductor I32, inner upper back contact of relay I55 of coin collect circuit CCM, winding of relay I65, back contact of relay I66, inner upper back contact of relay I85, conductor I42, a front contact of relay I09, brush I06 of trunk finder TFI, conductor 96, conductor 68, brush 12 of first selector SI, through the lower front contact of relay 84 and upper Winding of relay 85, to ground. Thus polarized relay I65 i operated in series with the calling subscriber's line and in series with the windings of relay 85 of connector switch CI as long as relay 84 remains operated due to the answer of the called subscriber at station B. The aforementioned operation of relay I6I connects the lower contact of interrupter springs I10, through the inner upper front contact of relay I 6!, outer lower back contact of relay I64 and lower back contact of relay I59 to the lower winding of relay I59. The upper and lower contacts of interrupter I10 are alternately closed for half a second; and, as soon after the operation of relay I6I as the lower contact of the interrupter springs is closed, the lower winding of relay I59 is operatively energized. Relay I59 closes a locking circuit, through its uppermost front contact, inner upper back contact of relay I64, conductor I62, and the inner upper front contact of relay NH; and closes a connection from ground at the inner lower back contact of relay I69, through the inner lower back contact of relay I64, resistor I51 and I54, inner upper front contact of relay I59 and inner lower back contact of relay I55 to conductor I3I and through the outer lower back contact of relay I85 to coductor I4I. As soon after relay I6I operates a the upper contact of interrupter springs I10 is again closed, ground is connected through the lower front contact of relay I59 to the lower winding or relay I53, thereby operatively energizing relay I53. Relay I53 closes a circuit through the upper winding of relay I59 for holding relay I59 operated, short-circuits resistor I54, short-circuits resistor I5I and condenser I52, connects ground to conductor I34 to maintain the energization of relay 64 of timing circuit TC, closes a circuit for operating relay I55, and connects the common tone source I50 in series with the right winding of transformer I15. The operation of relay I55 bridges the left windings of transformer I1I across conductors I3I and I32, so as to transmit to the calling ubscribers station, a tone indicating that the first interval for which a coin has been deposited is almost completed; and connects the coin collect battery CC, through the uppermost back contact of relay I64 and both left windings of transformer Hi to conductors I3I and I32, thereby effecting the operation of the coin magnet 1 at the calling subscribers station A to collect the deposited coin. Relay I55 also bridges the resistor I56 across conductors MI and I42 to hold the line relay 85 of the connector CI. This bridge is traced from conductor I4l, through the lowermost back contact of relay I85, resistor I56, the middle upper front contact of relay I55, winding of relay I65, back contact of relay I66, and inner upper back contact of relay I85, to conductor I42. The operation of relay I55 also short-circuits resistor I51 and closes a holding circuit for operatively energizing the upper; holdin winding of relay I53. When the lower. contact of the interrupter springs H0 is agamplosed, ground is connected through this contact, the inner upper front contact of relay I6I, a front contact of relay I53 and a back contact of relay I69 to operate relay I64. Relay I64 looks through conductor I62 to ground at a 2 front contact of relay I6I, disconnects coin collect battery CC from conductors I 3| and I32; connects ground at the inner lower back contact of relay I69, through the middle lower front contact of relay I64, a lower front contact of relay I53, inner upper front contact of relay I59, and outer lower back contact of relay I85, to conductor I4I; and'causes the release of relay I 55. The release of relay I55 opens the bridge comprising resistor I56 across conductor MI and I62, disconnects the left winding of tone transformer I1I from conductors I3I and I32, recloses the talking circuit between the calling and the called stations, and permits relay I53 to release. The release of relay I53 opens the short circuits across resistors I52 and I5 4, disconnects ground from conductor I34 to release relay 64 of timing circuit TC, and permits the release of relay I59. The release of relay I59 disconnects ground from conductors I3I and I4I. Thirty seconds after the closing of the contacts of cam 62 of timin circuit TC effects the connection of the trunk circuit CT to the coin control and monitor circuit COM for collection of the coin at the calling station A, the cam 6I closes its contact thereby connecting ground from conductor 53, through the uppermost front contact of relay 65, conductor 91, back contact of relay 63, outer upper front contact of relay 51, contact of cam 6I, inner upper front contact of relay 51, back contact of relay 66, conductor 96, brush I66 of trunk finder TFI, a front contact of relay I69, conductor I36, back contact of relay I53, inner upper front contact of relay I66, through the continuity contact and winding of relay I69 to battery, thereby operatively energizing relay I69 of the coin collect and monitor circuit CCM. Relay I69 locks under control of relay I6I and opens the operating circuit of relay I64, relay I66 being held perated under control of relay I6I. ,As soon after relay I69 operates a the lower contact of interrupter springs I16 is closed, ground is connected through this contact, inner upper front contact of relay I6I, outer lower front contact of relay I64, middle lower back contact of relay I12, a front contact of relay I69, and lower back contact of relay I59 to the lower winding of relay I59. Relay I59 operates; and it looks through its outer upper front contact, middle upper front contact of relay I69, and inner lower back contact of relay I12, to ground at the uppermost front contact of relay I6I. The operation of relay I59 again connects ground to conductors I3! and I6I, this connection being traced from conductor I4l through the outer lower back contact of relay I85, and from conductor I3I through the inner lower back contact of relay I55, thence through the inner upper front contact of relay I59, resistors I56 and I51, outer lower back contact of relay I12, to ground at the inner lower front contact of relay I69. As soon after the operation of relay I59 as the upper contact of interrupter springs I16 is again closed, ground is connected through this contact and the lower front contact of relay I59, to reoperate relay I53. Relay I53 again closes the holding circuit for relay I59, 7

short-circuits resistor I56, short-circuits resistor II and condenser I52, connects ground to conductor I34, and closes a circuit for operating relay I53. Relay I53 also connects tone source I56 to the right winding of transformer Ill;

but no stored to normal;

10 tone is transmitted to the calling station when relay I55 operates, because the operation of relay I69 disconnected the left windings of this transformer from the inner front contacts of relay I55; Relay I55 connects conductor I3I through its inner lower front contact, outer lower front contact of relay I69, and winding of relay I13 to the coin collect battery'CC; and connects conductor I32 through its inner upper front contact, uppermost front contact of relay I69, through resistor I68 to coin collect battery CC. If the subscriber at the station A has already deposited another coin, ground is connected through contact 6 and magnet 1 to the conductors of line LI to effect the operation of relay I13 without operating the coin control magnet 1; but, if no coin has been deposited, relay I13 does not operate. As soon as the lower contact of interrupter springs I16 is again closed, ground is connected through this contact, inner upper front contact of relay I6I, a front contact of relay I53 and a front contact of relay I59, to the winding of relay I 12. Relay I12 operates; and it looks through its continuity front contact, under control of relay I 85, through conductor I62, to ground at a front contact of relay I6I. The operation of relay I12 causes the release of relays I55, I53 and I59 thereby again establishing the talking circuit between the calling and called lines. If no coin was deposited, and relay I13 has not operated, the operation of relay I12 closes a connection from ground at the inner upper back contact of relay I58, through the middle upper front contact of relay I12, back contact of relay I13, upper back contact of relay I61, inner lower back contact of relay I85, outer upper back contact of relay I56, lower back contact of relay I66 to conductor I93, to effect the operation of relay 2I5 to signal a monitoring operator as hereinafter described. If relay I13 operates, due to the deposit of another coin, it is'held operated through resistor I14 and the outer lower front contact of relay I13, to ground at a front contact of relay I12. The operation of relay I13 closes a circuit for operatively energizing the lower winding of relay I66, this circuit being traced through the inner lower front contact of relay I13, middle upper contact of relay I12, to ground at a back contact of relay I58. Relay I66 looks through its upper winding and front contact toground at the front contact of relay I6I, disconnects ground from conductor M5 to release'relay 65 of timing circuit TC, disconnects the winding of relay I6I from conductor I43 to cause the release of relay I 6|, and connect ground toconductor I43. The release of relay I6I disconnects ground from conductor I46 causing the release of relay I69 of trunk finder TFI. The release of relay 65-reconnects conductors 61 and 66 to conductors 5i and 52 to maintain the connection between'the calling and called lines after the trunk finder TFI is restored to normal. The release of relay 65 disconnects conductor 91 from conductor 53 and reconnects battery to conductor 54 to effect the reoperation of relay 44. The release of relay I69 of trunk finder TFI closes a circuit for operating release magnet II 4 of the trunk finder, this circuit being traced through the lower frontcontact of the vertical off-normal prings III, upper back contact of relay II1, lowerback contact of relay I69 and lower back contact of relay I2I, to ground at the upper front contact of the vertical off-normal springs I I I. The operation of release magnet I I6 causes the brushes-of the trunk finder to be reand, when the shaft of the trunk finder witch reaches normal position, the vertical off-normal springs are restored to normal position, thereby causing the release of magnet 4. Relay I6! of the coin collect and monitor circuit CCM is slow in releasing so as to insure the release of relay'65 in the timing circuit TC before relay l6! disconnects ground from conductor I46. The release of relay l6l also opens the holding circuit for the upper winding of relay I60, relay I66 bein slow in releasing so as not to reclose the operating circuit of relay [5| until the trunk finder has been released. Relay |6l also disconnects ground from conductor I62 thereby causing the release of all other operated relays in the coin collect and monitor circuit CCM.

If the connection between the calling station A and called station B is maintained after relay 65 of timing circuit TC is released, relay 5'1 remains operated and starts a new cycle of operation of the timing circuit. the coin trunk circuit CT is reconnected to a coin collect and monitor circuit CCM four and one half minutes after the new timing cycle is started. The coin is collected and, at the end of a five minute interval, the test is made for the deposit of another com.

If the called subscriber restores the receiver to normal, relay 84 releases. The release of relay 84 reverses the current through conductors 5i and 52 so that relay 38 reoperates and relay 31 releases, thereby short-circuiting the winding of relay'39.. The release of relay 39 causes the release of relay 43 and short-circuits the winding of relay 38. The release of

relays

38 and 43 shortcircuits the winding and causes the release of relay 40. If thecall is released by the calling subscriber prior to the expiration of a four and a half minute interval, measured by the timing circuit TO, the coin trunk CT is not connected to a coin collect and monitor circuit CCM and, relay 44 having been operated, the collection of the coin at the station A is effected by the operation of relays 34 and 16 of the coin trunk CT in the manner hereinafter described. When the calling subscriber restores the receiver to normal, relay 85 of the connector Cl releases, in turn causing the release of relay 86. The release of relay 86 disconnects ground from

conductors

63 and 53 thereby causing the return of selector SI to normal inthe usual manner. In case the coin trunkCT is connected to the coin collect and monitorcircuit CCM at the time that the connection is released bythe calling subscriber, the disconnection of ground from conductor 53 causes the release of relay I61. The disconnection of ground potential from conductor 53 also causes the release of relay 51 of timing cirouit TC and causes the release of relay 14 of coin trunk circuit CT. The line finder LP! is held by ground connected to conductor l3 at the front contact of relay 35. Relay 26 release when ground is disconnected from conductor 53 and so also do relays 39, 43 and 40 in case these relays have not already been released due to the disconnection of the called subscriber. As soon after relay 26 releases as interrupter relay I1 is released, a circuit is closed from ground at the back contact of relay i1, inner lower front contact of relay 35, continuity back contact and winding of relay 34, to battery at a back contact of relay 26, thereby causing the operation of relay 34. Relay 34 locks under control of relay 35. When the interrupter relay i1 next operates, a circuit is closed from ground at the front contact of relay through the winding of relay l6, outer lower front contact of relay 34, and upper front contact'of relay 35, to battery at the lower back contact of relay 26 The operation of relay i6 connects coin collect battery CC through the inner lower front contact of -relay 44, winding of relay 23, lower front contacts of relay i6, back contactsof relay l4, conductorslland l2 and brushes of line finder LFI, to the conductors of line Ll to operate the coin collect magnet l to collect the coin. Relay '23 operates in series with the coin collect magnet, thereby insuring that relay 36 is held operated during the time that the coin is being collected. As soon as interrupter relay I! again releases, ground. is disconnected from the winding of relay i6 to cause its release and thereby disconnect the coin collect battery from the conductors of line Ll. When relay ll next reoperates, ground is again connected to operate relay 16 of the coin trunk circuit CT to again apply the coin collect battery to the line LI. If the coin has been collected by the first application of coin collect battery, there is no circuit for operating relay 23; and the operation of relay I6 causes the release of relay 36. The release of relay 36 causes the release of relay 35; and the release of relay 35 disconnects holding ground potential from conductor l3 thereby causing the release of the line finder LFI in usual and well-known manner. If the application of coin collect battery to the conductors of line L! fails to dispose of the coin, relay 23 is reoperated each time that the coin collect battery is applied to the line, thereby holding relays 36 and 35. In this case the connection of battery, through the upper front contact of relay 34 and lamp 22, to the alarm relay 2| cfiects the operation of an alarm a predetermined interval of time after the operation of relay 34.

If the calling subscriber replaces the receiver before the connection is completed, or before the call is answered, the opening of the line loop releases relay 33. The release of relay 33 causes the release of relays 32 and 29 and opens the bridge across conductor 51 and 52 to cause the release of the selector SI and the release of connector Cl if the connection has been extended thereto. Holding ground potential is thereby disconnected from conductor 53, causing the release of relay 26; but the line finder LE l is held ,i by the ground connected to conductor l3 at a front contact of relay 35. The release of relay 26 causes the operation of relay 34 as above described. The operation of relay 34 causes the operation of relay I6 under the control of interrupter relay i'l whereby coin return battery CE is connected through the upper front contact of relay [6, inner lower back contact of relay 44, winding of relay 23, front contact of relay l6, back contact of relay (4, conductors II and I2, brushes of linefinder LFI to the conductors of line Ll to operate the coin magnet I to return the coin. Relay 23 operates in series with the coin magnet thereby closing a holding circuit for relay 36. When coin return battery is connected to the conductors of line Li a second time, relay 23 fails to operate if return of the coin was effected by the first application of coin return battery, thereby causing the release of relay 36; and the coin trunk circuit is thereupon restored to normal as above described.

If the calling subscriber does not replace the receiver at the end of the five minute interval for which a coin has been collected by the coin collect and monitor circuit CCM and does not deposit another coin, the connection of ground to 13' conductor I93 causes the operation of relay 2I5 as hereinbefore described. The operation of relay 2I5 closes a circuit for lighting the lamp 22I at a monitoring operators position. When a monitoring operator answers the call by. inserting a plug 222 of a cord circuit CDI in the monitor jack 228, relay 2I3 is operated through the sleeve conductor. The operation of relay 2I3 causes the release of relay 2I5 and closes acircuit through conductor I97 and. the outer upper front contact of relay I72 for operating relay I87 of the coin collect and monitor circuit CCM. At its lower front contact, relay I67 closes a circuit for operating relays I58 and I 85. Relay I67 also closes a circuit for holding relay I72. Relay I 85 looks under control of relay I55; and relay I58 locks to ground at the front contact of relay ISI. The operation of relay I58 closes a circuit from ground at the upper back contact of relay I 80, through the outer lower front contact of relay I58, conductor I 44, a front contact of relay I89, brush I08 of trunk finder TFI, and conductor 98, for operatively energizing the upper winding of relay 63 of timing circuit TC. The operation of relay 83 causes the release of start relay 57 of the timing circuit whereby the timer is restored to normal and further timing is prevented until the monitoring operator hasdisconnected. Relay I85 connects the talking conductors I3! and I32 through conductors HM and I92 to repeating coil 209 to complete a talking connection with the answering operator, and bridges the retard coil I86 across conductors I GI and I42 to hold the line relay 85 of connector CI, thetalking connection between the calling and called stations being now traced through condensers IiS'I and I82. Relay 2-H is operated in series with the calling subscribers line, the operating circuit being traced from battery throughthe lower Winding of relay 2I I, lower back .contactof relay 205,- upper back contacts of relay 282,11pper left winding of repeating coil 208, conductor I9l, inner lower front contact of relay I85, inner lower back contact of relay I55, conductor I3 I, a front contact of relay I09 of trunk finder TFI, brush IIlI, conductor 9| conductor .51, outer upper front contact of relay 39, winding of relay 37,- lower front contact of relay I 4, conductor I2, middle brush of finder LFI, lower conductor of line LI, through the subscribers telephone, back overthe upper conductor of line LI, through the upper brush of line finder LFIz, conductor II, upper front contacts of relay [4, winding of relay 38, outer lower front contact of relay 39, conductor -2, conductor 92, brush I02of trunk finder 'I'FI, a front contact of relay I89 conductor relay I55, winding of relay I85, back contact of relay I266, middle upper front contact of relay I85, conductor I 82, lower left winding of repeating coil 2'09, lower back contact of relay 282, upper back contact of relay 285, through the upper winding of relay 2| I to ground. The operation of relay 2I-I opens the circuit through the upper winding of relay 2I3 thereby increasing the resistance of the circuit through the sleeve conductor of jack 228' to extinguish the supervisory lam-p (not shown) associated with the answering plug 222 of cord CDI. In case the subscriber wishes to deposit a coin for an additional period of time, the operator disconnects cord CDI from the monitoring jack 220 whereupon relay 2I3 releases. The release of relay 2| 3 causes the release of relay I67. The release of relay I87 closes circuits through resistors I83 and I 84- for discharging the condensers I81 and I82 and causes the I32, inner upper back contact of and ground is intermittently connected through the upper contact of interrupter springs- I70,=inner upper front contact of relay I58, middle upper front contact of relay I72, back contact of relay I73, upper back contact of relay I67, inner lower back contact of relay I 85, outer upper front contact of relay I58, front contact of relay I85, back contact of relay I66, conductor I93, and lower back contact of relay 2I3 to the winding of relay 2I5, causing the intermittent operation of relay 2I5 thereby to flash the answering lamp 22I to indicate to the monitoringoperator that the calledsubscriber has failed to deposit a coin after the'operator disconnected. The operator again answers the call by inserting the plug- 222 of the cord C2 in monitoring jack 220. The operator may also interrupt the talking circuit between the calling and the called subscribers by inserting the plug of a cord in the splitting jack 248. The insertion of a plug in splitting jack 248 causes the operation of the sleeve relay 200. The operation of relay 280 closes a circuit from ground at its front contact, through conductor I98 and the inner upper front contact of relay I87, to operate splitting relay I78. The operation of relay I78 disconnects conductors MI and I4 2 from conductors I3I and I32, and closes a talk-- ing connection from the tip and ring conductors 240, through conductors I95 and I98, front contacts of relay I78 and condensers IBI and I82 to conductors MI and I42, thence through trunk finder TF I selector SI and connector CI to the called subscrlbers line L2, thus enabling conversation between the operator and the called subscriber. If the called subscriber then disconnects and the subscriber at the calling station fails to disconnect, the release of relay 88 of connector CI causes a reversal of the current through the winding of relay I85 of the coin collect and monitoring circuit CCM, thereby causing the release of relay I85. When the monitoring operator disconnects, a circuit is closed for operating relay I88, this circuit being traced through the back contact of relay I65, the outer upper front contact of relay I58, inner lower back contact of relay I85, upper back contact of relay I87, back contact of relay I73, middle upper front contact of relay I72, inner upper front contact of relay I58, to ground through the upper contact of interrupter springs I78. Relay I66 lock through its upper front contact under control of relay I8I, and opens the .connection between talking conductors I32 and I92, thereby causing the release of relays 85 and 86 of connector CI so as to disconnect holding ground potential from

conductors

83 and 53 to effect the release of the connector CI and selector SI. Re"- lay 44 having been released when the cut-off relay 65 of the timing circuit operated, the discon-- nection of ground from conductor 53 causes the coin trunk CT to operate to return any coin in the coin box at the calling station A. If there is no coin in the coin box at station A, relay 3'6 releases as soon as relay I8 operates to apply the coin return potential; and, since relay 23 does not operate, relays 36 and Y35 release. The release of relay 35 disconnects ground potential from conductor I3; and the line finder LP! and coin trunk CT are thereupon restored to normal in the above-described manner.

On a call to the monitoring operator, the monitoring operator may insert the plug 231 ofva, coin collect or refund cord CCD in jack 230, thereby operating relay 204. The operation of relay 204 causes the operation of relay 262; and the operation of relay 202 connects conductors l9] and I 92 to the tip of jack 236. ,The operation of coin collectkey 232 or coin return key 233 connects coin collect or coin return battery potential through the tip of plug 23l and jack 236, front contacts of relay 202, conductors I91 and 192, front contacts of relay H35, to'conductors 131 and I32, thence to the calling line L1 to operate the coin magnet 1 of the calling subscribers station to refund or collect the coin, as desired.

, On a call from station A to a special service operator, the coin trunk CT operates in the manner hereinbefore described to close a bridge across conductors 5| and 52 to operate the line relay of selector SI; and holding ground potential is connected to conductor 53 in the usual manner. When the digit is dialed by the calling station, the brushes of selector SI are stepped up to the tenth-level. The normal post springs 16 are actuated when the brushes are on the tenth level thereby closing a circuit for operatively energizing the lower winding of relay 63. Relay 63 looks through its front contact and the outer lower back contact of relay 65, to conductor 53. The operation of relay 63 disconnects the winding of start relay 51 of timing circuit TC from conductor 91 so as to prevent the timer cams BI and 62 from being moved out of normal position on this call. The selector S1 is automatically operated to ad- Vance the brushes in the tenth level to hunt for an idle trunk to an operator. Assuming that the selector SI selects andseizes the terminals con nected to the trunk circuit BUT, the aforementioned bridge across conductors 5i and 52 is extended through brushes 1i and 12, conductors 251 and-252, back contacts of relays 254 and 261, left windings of repeating coil 285, and back contacts of relay 212 to the windings of relay 213. Relay 213 operates, closing a circuit for operating relay 214. Relay 214 closes a circuit for lighting the answering lamp 291; closes a connection from ringing current source 215, through the inner lower front contact'of relay 214, back contact of relay 264 and condenser 265, to the lower right winding of repeating coil 266 to transmit an audible ringing signal to the calling subscriber to indicate that an operator is being signaled; closes a circuit for operating the slow-to-release relay 261; and connects ground potential to sleeve conductor 253 to hold the selector Si and to hold relay 26 of the coin trunk circuit CT. When an 7 operator answers the call by inserting the plug of a cord CD! in jack 290, relay 286 is operated due to the energization of its upper, high-resistance winding in a circuit through the sleeve conductor of jack 296. Relay'lld having been operated, the circuit through the lower winding of relay 266 is open; so that the resistance of the sleeve circuit is high. enough to cause the supervisory lamp associated with the plug inserted in jack 2% to be extinguished. The operation of relay 266 closes a circuit for operating relay 212. Relay 212 closes a'circuit for operating relay 21 I and interchanges the connections between the windings of relay 213 and

conductors

251 and 252, thereby reversing the current through these conductors and conductors 5| and 52 of the coin trunkcircuit CT. This reversal is efiective to cause the operation of relay 14 to connect the calling line in serieswith the windings of relay 213. Relay 21I closes a. circuit for holding relay 251, closes a circuit for operating relay 264, and opens the circuit for lighting the answering lamp 29L The operation of relay 264 closes a locking circuitunder control of relay 261, and opens the circuit for transmitting a ringing tone to the calling station. The answering operator may refund the coin deposited at station A by inserting the plug 23! of a coin control cord CCD in jack 292 thereby operating relays 255 and 254 in succession. Operation of coin collect key 232 or coin return key 233 connects coin collect or coin return battery, through conductor 293 and front contacts of relays 255 and 254 to

conductors

251 and 252, thence through selector SI, coin trunk CT and line finder LFl, to the conductors of line L1 to operate the coin magnet 1 to effect the collection or return of the coin, as desired.

When the'operator releases the connection, relays 266'and 21l release in succession; and when the calling subscriber replaces the receiver, relays 213 and 214 release in succession. With both of relays 214 and 2H released, relays 261, 264 and 212 are released. When relay 261 releases, holding ground potential is disconnected from conductor 253 causing the return of the selector SI, coin trunk CT and line finder LE! to normal.

In case the recording completing trunk circuits to which the selector SI has access are arranged for automatic return of the coin at the calling coin station upon answer of the call, the selector Si is not provided with normal post springs for operating relay 63. Reference may be had to my Patent No. 2,336,866, granted Dec. 14, 1943 for a complete disclosure and description of a recording completin trunk circuit arranged to automatically effect the return of the coin at a calling coin station when the call is answered. When the coin station A is connected to such a recording completing trunk circuit and the call is answered, the reversal of current through conductors 5i and 52 eifects the operation of relay 38 and the release of relay 31 of coin trunk circuit CT, thereby causingthe operation of relay 44 as hereinbefore described. The operation of relay 44 connects conductor 91 to the grounded sleeve conductor 53 thereby causing the operation of relay l4 so as to connect the calling line directly to the line conductors of the recording completing trunk circuit; and relay 51 operates as hereinbefore described to start the operation of timing cams 6| and 62. As soon thereafter as the recording completing trunk circuit effects the connection of coin return battery to the incoming line conductors, as described in my aforementioned patent, the gas-filled tube 56 of timing circuit TC- is energized, causing the operation of relay 55. Relay 55 ,closes a circuit for operatively energizing the lower winding ofrelay 53; and the operation of relay 63 causes the release of relay 51 whereby the timer cams are restored to normal and further timing is prevented while the connection between the lineLl and the answering operator is maintained, 7

What is claimed is:

1. In a telephone system, lines and stations, a

subscribers prepay coin station connected to one of said'lines, said station comprising a coin con-.

trol rnagnet, for collecting or refunding coins,

means including a coin control trunk circuit for establishing connections between said one line and a called subscribers line, timing means individual to said coin control trunk circuit for measuring charging unit intervals of time, an operators position, a recording completing trunk circuit terminating at said position, means including said coin control trunk circuit for connecting said one line to said recording completing trunk circuit, means including means in said coin control circuit operative in response to answer of a call therethrough for initiating the operation of said timing means, a coin return battery, means in said recording completing trunk circuit eflective upon answer of a call therethrough from said coin station by an operator at said position for connecting said battery to said one line, means comprising a gas-filled tube individual to said coin control trunk circuit operatively responsive to the connection of the coin return battery to said one line for preventing the further operation of said timing means While the connection between said one line and said recording completing trunk circuit is maintained.

2. In a telephone system, lines and stations, a subscribers prepay coin station connected to one of said lines, said station comprising a coin control magnet for collecting or refunding coins, means including a coin control trunk circuit for establishing connections between said one line and a called subscribers line, timing means individual to said coin control trunk circuit for measuring charging unit intervals of time, an operators position, a recording completing trunk circuit terminating at said position, means including said coin control trunk circuit for connecting said one line to said recording completing trunk circuit, means including means in said coin control trunk circuit operative in response to answer of a call therethrough for initiating the operation of said timing means, a coin return battery, means in said recording completing trunk circuit efiective upon answer of a call therethrough from said coin station by an operator at said position for connecting said battery to said one line, means comprising a gas-filled tube individual to said coin control trunk circuit operatively responsive to the connection of the coin return battery to said coin line for effecting the return of said timing means to normal and for preventing the further operation of said timing means while the connection between said one line and said recording completing trunk circuit is maintained.

3. In a telephone system, lines and stations, a subscribers prepay coin station connected to one of said lines, an operators station, a coin control trunk circuit, means including said trunk circuit connecting said prepay station to 9, called station, a timing device associated with said trunk circuit for timing periods of conversation between said coin station and a called subscribers station, and means comprising a gas-filled tube in said trunk circuit actuated responsive to answer of a call to said operators station for preventing the operation of said timing device.

4. In a telephone system, lines and stations, a subscribers prepay coin station connected to one of said lines, an operators station, a coin control trunk circuit, means including said trunk circuit connecting said prepay station to a called station, a timing device associated with said trunk circuit for timing periods of conversation between said coin station and a called subscribers station, means for starting the operation of said timing device responsive to the answering of a call at the called station, and means comprising a gas-filled tube in said trunk circuit for immediately stopping the operation of said timing device on a call to said operators station.

5. In a telephone system, lines and stations, a subscribers prepay coin station connected to one of said lines, an operators station, a coin control trunk circuit, means including said trunk circuit connecting said prepay station to a called station, a timing device associated with said trunk circuit for timing periods of conversation between said coin station and a called station, means for starting the operation of said timing device responsive to the answering of a call at the called station, and means comprising a gas-filled tube in said trunk circuit for immediately effecting the return of said timing device to normal and for preventing its further operation on a call to said operators station.

6. In a telephone system, lines and stations, a subscribers prepay coin station connected to one of said lines, an operators station, a coin control trunk circuit, means including said trunk circuit connecting said prepay station to a called station, a timing device associated with said trunk circuit for timing periods of conversation between said coin station and a called station, relay means in said trunk circuit responsive to the answer of a call at the called station, means for starting the operation of said timing means responsive to the operation of said relay means, and means comprising a gas-filled tube in said trunk circuit actuated on a call from said calling station to said operators station for preventing the further operation of said timing device.

HENRY HOVLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,480,403 Lattig et a1. Jan. 8, 1924 2,251,301 Sobotta et a1 Aug. 5, 1941 1,488,784: Goodrum Apr. 1, 1924 1,738,290 Fowler Dec. 3, 1929 2,113,080 Crocker Apr. 5, 1938 1,799,653 Stokely Apr, 7, 1931 1,844,111 Stokely Feb. 9, 1932 1,804,408 Fowler May 12, 1931 1,823,040 Hague Sept. 15, 1931 1,917,884 Hague July 11, 1933