US2336866A - Telephone system - Google Patents

Description

Dec. 14, 1943. H. HOVLAND TELEPHONE SYSTEM 4 Sheets-Sheet 1 Filed Aug. 28, 1942 INVENTOR H. Hal LAND BY $19M 7 ATTORNEY Dec. 14, 1 943. 'H.'JHOVI'.AND 2,336,865

TELEPHONKSYSTEM Filed Aug. 28 1942 4 Sheets-Sheet 2 com mum cInca/r POLAR/Z50 H. HOVLAND ATTORNEY Patented Dec. 14, 1943 UNITED TENT OFFICE TELEPHONE SYSTEM Application August 28, 1942, Serial No. 456,483

6 Claims.

This invention relates to telephone systems and particularly to systems comprising coin stations of the prepayment type.

Objects of the invention are the improvement of systems comprising coin stations and particularly improvement of the line circuit apparatus associated with coin stations of the prepayment type thereby to increase the length of line over which satisfactory prepayment coin service is possible.

In automatic telephone systems it is known to provide an auxiliary line circuit including voice and signal repeating apparatus, if the associated line is a long or high-resistance line, to enable the completion and supervision of desired connections. This invention is a long line circuit associated with a coin station of th prepayment type arranged to repeatvoice currents, to repeat selective, ringin and supervisory signals, and to transmit coin control current for collecting and refunding coins deposited at the subscribers station. This line circuit is also arranged to mark the line busy as soon as the receiver is removed, or a leak condition exists, although no coin has been deposited; and arranged to start a line finder only in the case of a line leak of low enough resistance to operatively energize the impulse repeating relay so that the lin will be connected to a first selector and a permanent signal will be operated in well known manner.

The invention and its features will be better understood by considering a system in which the invention is embodied, one such system bein shown in the drawings which form 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 of the prepayment type.

Referring to the drawings:

Fig, 1 shows a coin subscriber's station A, a line LI, and an auxiliary line circuit ALC;

Fig. 2 shows a line circuit LC, a line finder LP, a first selector S, a coin trunk circuit CT interconnecting the line finder and first selector, a toll connector TC, and a local connector LCI;

Fig. 3 shows a local connector switch LCZ, a subscribers l ne L2 and called station E, a toll transmission selector TTS, and a coin control selector CCS Fig. 4 shows a recording and completing trunk circuit RCT terminating in answering and coin control jacks I30 and I40 at a toll operators position; Fig. 4 also shows a jack 230 connected to the toll transmission selector of Fig. 3 and a jack 240 connected to the coin control selector of Fig.

3; Fig, 4 also shows a cord circuit CDI used for establishing connections at the toll operators position, a cord CD2 used for automatically controlling the collecting or refunding of coins at a called subscribers station, and a cord CD3 used for manually controlling the collection or refund of coins on a call incoming to an operators position; and

Fig. 5 shows the relative position in which Figs. 1 to 4 inclusive, are to be placed to form an operative arrangement.

The subscribers station A is of the usual type provided at prepay coin stations in automatic telephone systems and comprises a dial 8 for selectively operating the selector and connector switches used in establishing connections. The station A also comprises coin apparatus comprising the contacts 6 which are closed by the deposit of a coin and a coin control magnet 1 for collecting or refunding deposited coins. Reference may be had to the patent to O. F. Forsberg, No. 1,043,219, of November 5, 1912, for a description of a coin box for use at a prepayment coin station. The line finder switch LF, connector switches LCI, LCZ and TC, and selector switches S, TTS and CCS are all of the two-motion step-by-step type. Reference may be had to pages 53 to 67, inclusive, of the second edition of Automatic Telephony, by Smith and Campbell, for a description of the structure of switches of this type and for a description of the operation of such switches when used as local selectors and connectors. Reference may be had to the patent to R. L; Stokely No. 1,799,654, granted April '7, 1931, for the description of the operation of a step-by-step switch when used as a line finder. Reference may be had to the patent to Stokely 1,653,789, granted December 2'7, 1927, for a description of the operation of such switches when used as toll transmission selectors and toll connectors. Reference may be had to the patent to R. L. Stokely No. 1,586,537, granted June 1, 1926, for the description of a two-motion step-by-step switch used as a coin control selector. The coin trunk CT is similar to that disclosed in the patent to B. G. Dunham No. 1,569,623, granted January 12, 1926.

A clear and complete understanding of invention and its application in the system shown in the drawings will be facilitated by a description of the operations involved on local and toll calls initiated at station A. Assume first that the subscriber at station A removes the receiver to initiate a call. A circuit is thereupon closed from battery through the winding of relay I9, inner upper back contact of relay 29, middle lay 32 to ground. Relay 32 operates but relay l9 does not operate at this time because it 'is marginal and relay 25 is held non-operated by its lower, biasing winding. Relay 32 is so adjusted that it will not operate due to line leak unless the line leak is of 'lowenough resistance to operate relay 25 as hereinafter described. The operation of relay 32 closes a circuit for operating the slow-to-release relay 3|; and relay.

3| closes a circuit for operating relay 38. The

operation of relay 38 closes a bridge across conductors 4| and 42 to operate line relay 45 of line circuit LC. This circuit is traced from battery through the right winding of relay '45, inner back contact-of cut-off relay 46, conductor 42, upper front contact of relay 3|, outer upper front contact of relay 30, inner lower back contact of relay 29, lower right winding of repeating coil 22, resistor 24, upper right winding of repeating coil 22, conductor 4|,-through the outer back contact of relay 46 and left winding of relay 45 to ground. The aforementioned operation of relay 3!! disconnects the winding of relay 8 and the winding of cut-01f relay 48 of line circuit LC from conductor '43, connects ground to'conductor 43 to mark this line busy in the banks of connector switches LCI and TC, and opens the normally closed circuit for energizing the lower, biasing winding of relay 25 to cause the; operation of relay 25 and thereby close the bridge across conductors 4| and 42 independent of relays 28, 38 and 3|. The operation of relay 45 closes a circuit for operating the group relay 41 and connects the winding of relay 46'to sleeve conductor 48. The operation ofgroup relay 4! closes a circuit for starting the operationiof an idle line finder LF; and when the brushes of-thepline finder engage the termine-l5 50,the cut-through relay (not shown) of line finder LF is operated in the manner described in 'the aforementioned patent to R. L. Stokely, x No. 1,799,654. The connection of ground to conductor 53, when the cut-through relay of the line finder operates, causes the ation of relay |8 closes a locking circuit for relay 30.

Sincean auxiliary line circuit is provided only for those lines which are long enough to require the use. of such a circuit, the line finder LP includes normal post springs NP which are actuated when the brushes are on a level in which each of the lines is provided with a long linev circuit. If the;calling line to which the brushes of linefinder LF are connected is a line which is not a long line, the normal post springs NP are not actuated and in this case the associated coin trunk CT tests for the deposit of a coin and connects the impulse repeating relay 16 to the'calling line. If the calling line is one with which a long line circuit ALC is associated, the normal post springs NP are actuated and in this case the test for the deposit of a coin is made by the long line circuit and dial impulses are rep eated by the long line circuit directly to the first selector. The operation of the cut-through relay of the line finder closes a circuit for operating the line relay 68 of coin trunk CT. This circuit is traced from battery at the upper back contact of relay 58, inner lower back contact of relay 58, inner lower back contact of relay 68,

resistor 69, inner upper back contact of relay 55, lower back contacts of relay 54, conductor 52, middle brush of line finder LF, conductor 42, front contact of relay 25 of the auxiliary line circuit ALC, lower right winding of repeating coil'22', resistor 24, upper right winding of re peating coil 22, conductor 4|, brush and conductor 5| of line finder LF, upper back contacts of relay 54, lower back contact of relay 55, retard coil 56, and winding of relay 68, to ground at a back contact of relay 68. Relay 6!] closes a circuit for operating slow-to-release relay 18 and connects ground through the upper back contact of relay H and inner upper back contact of relay 68, to conductor 53 to holdtheline finder LF. This ground connection is further extended through the lower brush of line finder LF and conductor 48 to hold cut-off relay 46 of line circuit LC and relay I8 of auxiliary line circuit ALC. The aforementioned operation of relay 18 closes a circuit for operating relay 68. Relay 68connects ground directly to conductor 53 to hold the line finder LF and to hold the cut-off relay 48 of line' circuit LC and relay 18 of auxiliary line circuit ALC. The operation of relay 68 also opens the'circuit path through resistor 68 and closes a circuit path from battery at the back contact of relay 58, through i the inner lower back contact of relay 59, inner lower front contact of relay 68 and the winding of relay 51, thereby including the winding of relay 51in series with the winding of relay 68. Relay 5? is marginal and does not operate on the call in question since the test for deposit of a coin is made by the auxiliary line circuit ALC as hereinafter described. (On a call from a line not provided with a long line circuit, relay 51 operates when a coin is deposited at the calling station.) The operation of relay 68 opens the short circuit around resistor 62 thereby to increase the non-operating margin of relay 51. The aforementioned operation of relay 68 also closes a bridge across conductors 8| and 82 of selector '3 to operate the line relay (not shown) in usual manner. This bridge is traced from conductor 8|, through the upper back contact of relay 8!], winding of polarized relay l8, retard coil Ti, resistor 15, outer upper back contact of relay 14, outer lower front contact of relay 68, and lower back contact of relay 88, to conductor 82. The operation of the line relay of selector S causes holding ground potential to be connected to sleeve conductor 83 in the usual and well known manner, thereby causing the operation of relay 54. Relay 54 connects conductors 4| and 42 to the line conductors 8| and 82 of selector S so that the line relay of selector S is held operated by the aforementioned bridge across conductors 4| and 42 of auxiliary line circuit ALC. The operation of relay 56 causes the release of relays 63, i9 and 68 in the order named. Relay 54 also closes a circuit for operating relay i and relay 59 looks under control of relay 58. At its middle upper front contact, relay 59 connects the winding of relay it to the inner upper back contact of relay 55; but, with relay 5% operated, the'winding of relay it is not connected to conductor 52 for response to dial impulses, as would be the case on a call from a line not provided with a long line circuit. Relay H3 does not operate in series with the line relay of selector S since the current through its winding is in the non-operate direction until the current is reversed due to answer of the called subscriber as hereinafter described. At its outer lower front contact, relay 5'9 closes circuits for operating relays H and 72, the circuit for operating relay H including the outer upper back contact of relay 55. The operation of relay it closes a circuit for holding relay '5! locks relay #2 operated under control of relay 55. Relay H connects ground to conductor 53 to hold the line finder LP, the cut-off relay 28 of line circuit LC and relay 88 of line circuit ALC.

Dial tone is transmitted to the calling subscriber from the selector S, through repeating coil 22. of line circuit ALC, to the calling subscriber. The subscriber thereupon deposits a coin which actuates contacts 5 to connect ground through the windings of coin magnet 'l to both conductors of line Li, thereby increasing the current through the winding of relay :9 of line circuit ALC sufiiciently to cause the operation of this relay. The operation of relay i9 closes a circuit including front contacts of relays El and 98 for operating relay 29. Relay it opens one of the connections between the lower right winding of repeating coil 22 and conductor 32, but the bridge across conductors t! and :2 is maintained through the front contact of relay 25. Relay 2%) locks to ground at 2. fr nt contact of role" '8, includes one filament of lamp 2! in series with the middle winding of relay in place of the wind ng of relay includes the other filament of lamp 25 in series with the oper Winding of relay 25 in place of the winding of relay 32, and closes the circuit through resistor 28 for energiz g the biasing winding of relay 28 to condition re 23 forresponse to dial .pulses.

If a coin. is deposited at station A prior to removal of the receiver, relay 32 may or may not operate; but relay is is operated due to the clo-- sure of coin contact 5. If relay 32 does not operate, relays 3! and iii are not operated and the operation of relay it short circuits the winding of relay 32. Relay 25 operates over the calling subscribers loop, closing the bridge across conductors as and 4? to operate line relay so as to start idle line finder and extend the connection to a coin trunk CT, through which the connection is further extended to a first selector S. When. ground is connected to conductor 53 as above described. relays M and it are operated. The oper tion of relay iii closes a circuit for operating relay 29, to ground at the inner lower back contact of relay if this relay is not operated; or to ground at the front contact of relay it, if relay 3% is operated. If relay Ed is not operated. the ground connected to conductor 53 is extended through conductor d8, front contact of relay 55, conductor and middle lower back contact of relay to conductor to mark the l ne Li out; in the banks of connectors LCI and TC.

When the calling subscriber dials the first digit of the number of a station B with which a connection is desired, relay 25 is alternately released and reoperated as many times as there are units in the digit dialed, each dial impulse being repeated by the opening of the bridge across conductors iii and 42 at the contacts of relay 25 to selectively operate the selector S in Well-known manner. The trains of impulses created by the dialing of the succeeding digits of the called subscribers number are in like manner repeated by relay 25 to operate intermediate selectors, if any (none being shown), and to operate a connector LS2 to extend the connection to the called line Ll. The ringer at the called station B is operated in usual manner; and, when the call is answered, a supervisory relay in the connector effects a reversal of the current through conductors 8i and 32 causing the operative energization of the winding of polarized relay E8 of coin trunk CT. Relay l8 closes circuits for operating relays it and Relay is locks to conductor 53 and connects coin collect battery CC to the winding of relay #3. Relay 8!! looks to grounded conductor 83, closes a circuit for operating relay 85, and interchanges the connections between conductors 5! and 52 and conductors 8i and 82 so as to again reverse the current through the winding of relay l8. Relay opens the operating circuit of relay 8i] and prepares a short circuit for relay 3B; which short circuit closed when relay it reoperates, if the called subscriber is first to replace the receiver as hereinafter described. The tall:- ing connection between the calling and called stations includes repeating coil 22 of line circuit ALC.

When the calling subscriber restores the receiver to normal position at the end of conversation, relay 25 releases. The release of relay 25 opens the bridge across conductors M and 42, causing the release of the line relay (not shown) of the connector L62; whereby ground is disconnected from the terminal engaged by brush 53 to cause the release of selector S and the release of relays 54 and 59 of coin trunk circuit CT. The connector LCZ is restored to normal in the usual manner after both the calling and called subscribers have placed the receiver in normal position. As soon after relay 5% releases as the pickup interrupter $8 next closes its upper contact, relay 58 operates; and it looks to ground at the front contact of relay ii, independent of the interrupter. Relay 5t disconnects battery from resistor 69 to prevent the connection of this battery to conductor 52, the release of relay 5*! having connected conductors 5i and 52 to the contacts of relay 55. As soon after relay 53 operates as the interrupter 86 closes its lower contact, relay. 55 operates. If the call was answered and relay "M is operated, the operation of relay 55 connects coin collect battery CC, through the winding of relay it, front contacts of relay 55 and back contacts of relay 5d, conductors ill and 52, and brushes of line finder LP to conductors 4i and 42 of line circuit ALC. If the call was not answered and relay M is not operated, the operation of relay 55 connects coin return battery C3 to conductors ii and '22 of line circuit ALC. While the central office battery potential is insufficient to break down the gas-filled tube iii, the connection of either the coin collect or coin return battery to conductors i! and d2 affects the break down of this tube and operation of relay ll. The operation of relay l'l closes a circuit for operating relay 1 5 thereby connecting conductors ti and t2 e y to the conductors of line Ll to effect the operation of 'coin control magnet 1 at station A. If coin collect battery is connected to these conductors, the magnet 1 is operated to collect the coin; if coin return battery is connected to the line conductors, the magnet 1 operates to return the coin. While magnet 1 is being operated, relay 13 of coin trunk CT operates, closing a holding circuit for relay 12. As soon after relay 55 operates as the lower contact of inter rupter 86 is opened, relay'55 releases disconnecting the coin collect or coin refund battery from conductors 5| and 52, thereby deenergizing tube I6 and releasing relays l1, I5 and 13. The next closure of the lower contact of interrupter 86 again operates relay 55 to connect the coin control battery to the line; but, the coin having been either collected or refunded as the case may be by the first application of coin control battery, there is no ground connection at the coin box and relay 13 does not operate. With relay 55 operated and relay 13 normal, there is no circuit for holding relay 12 operated and consequently relays 12 and 1| release, in succession. When the lower contact of interrupter 86 is next opened, relay 55 releases, tube I6 deenergizes, and relays I1 and I5 release. The release of relay 1| disconnects holding ground potential from conductor 53 thereby causing the release of relays 58, 46 and I8, the release of line finder LF and the release of relay 14, if operated. If relay 30 is not operated, the release of relay 1| effects the disconnection of ground potential from the sleeve terminal of line LI in the banks of the connectors LCI and TC. If operated, relay 30 releases when relay I8 releases, disconnecting ground from conductor 43. The release of relay I8 also causes the release of relay 29 thereby completing the restoration of line circuit ALC to normal.

If the subscriber at station A makes a toll call, the selector S is operated to select the level in which the terminals are connected to recording completing trunks and to select an idle trunk in the group. Such a level and trunk are represented in the drawings by terminals 95, which are connected by a three-wire trunk to the trunk circuit RCT terminating at a toll operators position. Upon selection of trunk circuit RCT, the bridge across conductors 4| and 42 is extended to conductors IM and I02, thereby causing the operation of relay I22. Relay I22 operates relay I23. Relay I23 connects holding ground potential to conductor I03, lights the answering lamp I3I, closes a circuit for operating relay H4, and connects the ringing current source I24, through condenser H2 to repeating coil I20 to transmit a ringing tone to the calling station. The connection of ground to conductor I03 holds selector S. 7

When the call is answered by inserting the plug 23| of a cord CDI in jack I30, relay H3 operates. Relay I I3 closes a circuit for operating relay H9. Relay H9 closes a circuit for operating relay I I8 and interchanges the connections between the windings of relay I22 and conductors IOI and I02 to reverse the current therethrough so' as to effeet the operation of relay 18 of coin trunk CT. Relay H8 extinguishes the answering lamp and closes circuits for operating relays III and H4. Relay IIIopens the ringing tone path through condenser H2 and operates relay H6. Relay H4 connects holding ground to conductor I03 and locks relay III. The operation of relay H6 closes a circuit for holding relay I23-and connects the winding of relay I09 to interrupter H1, the brush of which is connected to ground once every second. The operation of relay I09, to ground through interrupter H1, closes a circuit through the upper winding of relay I01. Relay I01 operates, looks through its lower winding under control of relay H4, and closes a circuit for operating relay I04. Relay I04 disconnects conductors I0| and I02 from the windings of relay l22, and closes a holding circuit for relay H6. With relays I01 and I04 operated, coin return battery CR is connected to conductors I0| I and I02, thence through brushes 9| and 92, front contacts of relay 80, front contacts of relay 54, conductors 5| and 52 and brushes of line finder LE to conductors 4| and 42 to effect the operation of tube I6 and relays I1 and I5, thereby extending the coin control circuit over line LI to operate coin control magnet 1 to refund the deposited coin. When the interrupter ground is opened, relay I09 releases causing the operation of relay l06. Relay I06 locks under control of relays I05 and III, and closes a circuit for holding relay |04 operated. When relay I09 next operates under control of interrupter H1, the locking winding of relay I01 is short-circuited and relay |01 releases. The release of relay I01 opens the coin return battery connection. When relay |09 next releases, it closes a circuit for operating relay I05. Relay I05 locks under control of relay III, causes the release of relays I06, I04 and H6 in succession and renders the coin control jack I40 effective for subsequent use in disposing of coins. The release of relay I04 reconnects conductors IOI and I02 to the windings of relay I22; and the release of relay H6 opens one of the paths for energizing the winding of relay I23, and disconnects the winding of relay I09 from interrupter H1. Thereafter coins may be collected or refunded by insertion of plug |4| of coin control cord CD3 in jack I40 and operation of coin collect key I42 or coin return key I43, relay I I5 being operated in either case to efiect the operation of relays H6 and I04 in succession. With relays I04 and I05 operated, the coin collect or coin refund battery is connected to conductors IIlI and I02 to effect the collection or refund of any coins deposited at station A.

If a toll call from station A is completed on a delayed call basis, the toll operator establishes connection with the line LI through a switching trunk ST, a plug of a cord CDI being inserted in jack 230. The toll transmission selector TTS and a toll connector TC are selectively operated under the control of the toll operators dial to establish connection with the terminals to which conductors 4|, 42 and 43 are connected. The cut-off relay 46 of line circuit LC and sleeve relay I8 of line circuit ALC-are operated upon seizure of these terminals by ground Potential connected to the sleeve brush of the connector TC in the usual manner. Relay 46 disconnects the line relay 45, and relay I8 efifects the operation of relay 29, thereby connecting relay 25 to the left windings of repeating coil 22 for operation when the call is answered. The toll connector TC connects a ringing source (not shown) to conductors 4| and 42 thereby operatively energizing the winding of relay 20 which is normally connected in series with condenser 26 across these conductors. Relay 20 closes a circuit for operating relay |5 whereby conductors 4| and 42 are connected directly to conductors II and I2 of line LI so as to operate the ringer at station A. When the call is answered at station A the ringing cur-= rent-circuit is opened in the connector, releasing relays 20 and I5; and the talking circuit is closed through the connector TC and toll transmission selector TTS. Relay operates to bridge the right windings of repeating coil 22 across conductors 4| and 42 thereby operating the answering supervisory relay in the toll transmission selector in the usual manner. The toll operator may now dispose of coins by inserting the plug 24! of a coin control cord CD2 in jack 249 associated with coin control trunk CCT and coin control selector CCS. By dialing the required code, selector CCS is operated to connect with the toll transmission selector 'ITS. Relay I58 is controlled by relay 243 of the cord CD2 to connect coin collect battery or coin return battery through contacts of relay I60 of toll transmission selector TTS to effect collection or refund of coins at station A, the coin control battery being applied through line circuit ALC in the manner hereinbefore described. When the connection is released, relays 46, I8 and 29 are released restoring the line circuits to normal.

If the receiver is removed at station A without depositing a coin, or a leak condition of low enough resistance exists, relay 32 of auxiliary line circuit ALC is operated as hereinbefore described. Relay 32 causes the operation of relays 3| and 38 whereby ground potential is connected to conductor as to mark the line Ll busy in the banks of connectors LC! and TC; and the call is extended through a line finder to a selector in the manner hereinbefore described. After this condition has existed for a predetermined interval of time, a permanent signal alarm is operated in the usual and Well-known manner.

What is claimed is:

1. In an automatic telephone system ccmprising subscribers stations including coin-box stations, comprising means for applying a ringing source to called lines and comprising coin collect and coin refund batteries for connection to coin subscribers lines to effect the collection or return of coins deposited at the coin subscribers stations as desired, a line, a subscribers station connected to said line, said station comprising a directive impulse sender and coin-box mechanism for receiving and collecting or refunding coins, a line circuit individual to said line, said line circuit comprising a line relay and a line cut-off relay for disconnecting the incoming line conductors of said line circuit from said line relay, and an auxiliary line circuit connectin the first-mentioned line circuit to said line, said auxiliary line circuit comprising means responsive to the removal of the receiver at said coin subscribers station for causing the operation of said line relay, voice current repeating means normally connecting the conductors of said line to the talking conductors of said line circuit, means for repeating directive impulses created by the operation of said sender, means responsive to the application or" a ringing source to the talking conductors of said firstmentioned line circuit for connecting said conductors directly to said line, and means responsive to the application of coin collect or coin refund battery to the talking conductors of said line circuit for connecting said conductors directly to said line.

2. In an automatic telephone system comprising lines, a paystation connected to one of said lines, said station including a telephone instrument adapted to be connected across the conductors of said line by removal of the receiver from its normal position and including coin receiving means for connecting ground potential to the line upon deposit of a coin therein, a line circuit for said line comprising line and line out-- ofi relays, and an auxiliary line circuit for said line, said auxiliary line circuit comprising two relays normally connected to said line, one of said two relays operatively responsive to removal of the receiver at said station, the other of said relays responsive only to the removal of the receiver and deposit of a coin in the coin receiving means thereat, means responsive to operation of said one of the two relays for closing a circuit for operating said line relay, and means responsive to the operation of the other of said two relays for closing an impulse repeating bridge across the line conductors of said first-mentioned line circuit.

3. In an automatic telephone system comprising lines, a paystation connected to one of said lines, said station including a telephone instrument adapted to be connected across the conductors of said line by removal of the receiver from its normal position and including coin receiving means for connecting ground potential to the line upon deposit of a coin therein, a line circuit for said line comprising line and line outofi relays, and an auxiliary line circuit for said line, said auxiliary line circuit comprising two relays normally connected to said line, one of said two relays operatively responsive to removal of the receiver at said station, the other of said relays responsive only to the removal of the receiver and deposit of a coin in the coin receiving means thereat, means responsive to operation of said one of the two relays for closing a circuit for operating said lin relay, means responsive to the operation of the other of said two relays for closing an impulse repeating bridge across the line conductors of said first-mentioned line circuit, and means responsive to the operation of said one of said two relays for marking said line busy prior to the deposit of a coin at said station.

4. In an automatic telephone system comprising lines, a paystation connected to one of said lines, said station including a telephon instrument adapted to be connected across the conductors of said line by removal of the receiver from its normal position and including coin re ceiving means for connecting ground potential to the line upon deposit of a coin therein, a line circuit for said line comprising a line relay and a line cut-off relay, an auxiliary line circuit in terconnecting said line and th first-mentioned line circuit, said auxiliary line circuit comprising three relays normally connected in series to the conductors of said line, a first one of said relays being operatively responsive to removal of the receiver at said station, a second one of said relays being operatively responsive only to removal of the receiver and the deposit of a coin at said station, and means responsive to the operation of said first relay for marking said line busy prior to the deposit of a coin at said station, for closing a bridge across the line conductors of the first-mentioned line circuit to operate aid line relay and for rendering said third relay operative in series with said first and second relays, the operation of said third relay efiective to close a bridge across the line conductors of the firstmentioned line circuit independent of said first relay.

5. In an automatic telephone system comprising lines, a paystation connected to one of said lines, said station including a telephone instrument adapted to be connected across the conductors of said line by removal of the receiver from its normal position, including coin receiving means for connecting ground potential to the line upon deposit of a coin therein and including directive impulse sending means, a line circuit for said linecomprising a line relay and a line cut-off relay, an auxiliary line circuit interconnecting said line and the first-mentioned line circuit, said auxiliary line circuit comprising three relays normally connected in series to the conductors of said line, a first one of said relays being operatively responsive to removal of the receiver at said station, a second one of said relays being operatively responsive only to removal of'the receiver and the deposit of a coin at said station, means responsive to theoperation of said first relay for marking said line, busy prior to the deposit of a coin at said station, for closing a bridge across the line conductors of the first-mentioned line circuit to operate said line relay and for rendering said third relay operative in series with said first and second relays, the operation of said third relay efiective to close a bridge across the line conductors of the first-mentioned line circuit independent of said first relay, impulse controlled automatic switches for interconnecting calling and called lines, means responsive to the operation of said line relay for connecting the line conductors of said first-mentioned line circuit to a first one of said switches, means effective upon connection of said first-mentioned line circuit to a first one of said switches to operate said cut-off relay,

means operative in response to the operation of said second relay and the connection of said first-mentioned line circuit to a first one of said switches for disconnecting said first and second relays from said line and for connecting said third relay inseries with said line for response to directive impulses created by the operation of the impulse sender at said station, said third relay being effective to repeat said impulses to selectively operate automatic switches to establish a connection with. a called line.

6. In an automatic telephone system comprising lines, a paystation connected to one of said lines, said station including a telephone instrument adapted to be connected across the conductors of said line by removal of the receiver from its normal position, including coin receiving means for connecting ground potential to the line upon deposit of a coin therein and including directive impulse sending means, a line circuit for said line comprising a line relay and a line cut-off relay, anauxiliary line circuit interconnecting said line and the first-mentioned line circuit, said auxiliary line circuit comprising three relays normally connected inseries to the conductors of said line, a first one of said relays beingoperatively responsive to removal of the receiver at said station, a second one .of said relays being operatively responsive only to re moval of the receiver and the deposit of a coin at said station, means responsive to the operation of said first relay for marking said line busy prior to the deposit of a coin at said station, for closinga bridge across the line conductors of the first-mentioned line' circuit to operate said line relay and for rendering said third relay operative inseries with said first and second relays, the operation of said third relay efiective to close a bridge across the line conductors of the first-mentioned line circuit independent of said first relay, impulse controlled automatic switches for interconnecting calling and called lines, means responsive to the operation of said line relay for connecting the line conductors of said first-mentioned line circuit to a first one of said switches, means effective upon connection of said first-mentioned line circuit to a'first one of said switches to operate said cut-off relay, means operative in response to the operation of said second relay and the connection of said first-mentioned line circuit to a first one of said switches fordisconnecting said first and second relays from said line and for connecting said third relay in series with said line for response to directive impulses created by the operation of the impulse sender at said station, said third relay being effective to repeat said impulses to selectively operate automatic switches to establish a connection with a called line, said first relay being operatively responsive to a line leak only in case said line leak is of low enough resistance to maintain the operative energization of said third relay after connection of said line circuits to one of said automatic switches.

HENRY HO V LAND.

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