US1595095A - Measured-service telephone system - Google Patents

Description

Aug. 10,1926. 1,595,095

V. E. HOFFMAN v MEASURED SERVICE TELEPHONE svs'mu Filed Dec. 50, 19 2 2 Shea s-shut 1 I l Q {d k //z A. i

Im.ren ur+- v Unc EHnJTman Aug. 10 1926. 1,595,095

v. E. HOFFMAN MEASURED SERVICE TELEPHONE SXSTEM Filed Dec. 30, 1922 2 Sheets-Sheet 2 4Z2 Eff- Patented Aug. 10, 1926.

UNITED STATES VANCE E. HOFFMAN, OE CI-IICAGQ'ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- wnnn.

'MEAsunEn-snnvmn TELEPHONE SYSTEM.

Application filed December 30, 1922. Serial No. 609,855.

The present invention relates in general to measured service telephonesystems, but

is more particularly concerned with systems i of this character in which automatic switches are used for connecting calling and called lines; and the object of the invention is the provision of new and useful meter controlling equipment and circuits which are adapted for use in controlling the operation of meters to assess variable charges. depending upon class of the line calling, the particular connection established, and the time the talking connection is maintained.

Other minor features of the invention will be pointed out in the detailed description and claims which follow.

Referring to the drawings, Figs. 1 and 2 are circuit diagrams which show only a portion of the apparatus required to complete a connection between a calling and a called subscriber; but in view of the Well known character of the apparatus, and of the fact that telephone systems of this character are now well understood, it is believed that suficient has been shown to enable the inven tion to be readily understood. Figs. 1 and 2 show how Figs. 1 and 2 may be slightly modified where conditions are different, as will subsequently be. explained.

In Fig. 1, the substation indicated by reference character A is an ordinary automatic substation which comprises the usual talking equipment and ringer, and also a calling device S, through the medium of which the subscriber controls the central office switches.

The line conductors 1 1 and 12 ext-end to the exchange where they terminate in the rotary line switch G, which may be briefly described as a line switch whose wipers have a rotary movement in a forward direction only, and which have no normal position, 'that is, 'when the switch is released the wipers do not return to normal but remain on the set of contacts last used. A plurality of these individual line switches may be given access to a group of trunk lines extending to first selector switches, and one of the trunk lines to which the line switch C has access is shown in the drawing as extending to the first selector D. The selector D is vertical and rotary switch of familiar construction, and together with a plurality of similar selectors, has access to a plurality of groups of trunk lines.

In the drawing I have shown two sets of contacts in the first and second levels of the selector D. but it is understood that the selectors will have ten levels corresponding to ten diiferent groups of-trunk' lines. 'One of the trunk lines terminating in the first level is the trunk line comprising conductors 7780, inclusive, which extends to the repeater B (Fig. 2) and then continues by way of conductors 200 and 201,- to a distant exchange, where the conductors 200 and 201 terminate in the line relay of a second selector switch. The repeater R has the usual functlon of a repeater in a two-wire 'automatictelephone system, but has been modified to performadditional functions which will be pointed out shortly. j

The relays, such as 51, for example, which have their lower portions shaded are of the type which are relatively quick to pull up, but which are .slow'to release, whereas relays, such as 14 of the line switch C, which have their cores partly shown in solid black are of the type which are both slowto pull up and slow to fallback.

In the system contemplated herein, the

exchange to which the trunk line comprising conductors 200 and 201 extends is a switching center or distributing point for a num ber of other exchanges, and includes second and third selectors (in some cases the third selectors may be in a third exchange) by means of which calls are routed to the exchanges'in which the called lines are located. It will be evident, then, that after a call has been extended as far as the repeater R, two more digits must be called before the exchange to which the call is going is definitely determined, and since the charge for the call is to be'in accordance with the terminating exchange, some means must be provided for registering" the second and third digits in order that the proper charge can be assessed. This means comprises the switch S, which is individual to the repeater R. The switch S is a vertical and rotary switch having 100 contacts arranged in rows or levels and a wiper 130 for engaging such contacts.

Now since the'meter used is of the type usuallyused in counting the number of co1npleted outgoing calls, and further since in the present case it is required to register the actual time during which conversation takes place, it is necessary to provide means for periodically operating it at a speed determined by the amount which is to be charged per time unit for the particular connection established, and in some instances, upon the class to which the calling subscriber belongs.

In the present case the means for periodicomplish this result it has been provided with a permanent magnet 152, which provides a means for insuring both a quick make and a quick break of the contacts.

In order to make clear just how the magnet is made to accomplish this result the op eration of the thermostat may be briefly described as follows: The thermostat bar normally rests against the contact screws 156 and 154 with considerable tension, which the magnet 152, pulling on the pole piece 155, is unable to overcome. l/Vhen the winding is energized, however, and the bar begins to heat up, this tension is gradually reduced, for the compound bar tends to curve downwardly because of the unequal expansion of its two parts. At a certain temperature the tension of the bar against its contacts becomes reduced to a POIIIL where it can no longer withstand the pull of the magnet, whereupon the bar is quickly pulled down until residual screw 151 engages the pole of the magnet. This operation breaks the circuit through the thermostat winding and the bar begins to cool oft. It is held by the magnet, however, until the cooling process has proceeded to a considerable extent, because the pole piece 155 is now relatively close to the magnet pole and is strongly attracted. Eventually the bar cools enough so that the magnet can no longer hold it and it flies back to its initial position, making firm contact again against the contact screws 156 and 154. The initial tension is adjusted by means of screw 150 and the point at which the bar is released by magnet 152 is adjusted by means of brass residual screw 151, from which it will be understood that the operation can be adjusted over a wide range of temperatures, while the rate can be varied to a considerable extent tor any given temperature.

Having described in a general way the apparatus shown herein, I willnow describe the operations which take place during the establishment of the connection. It will be assumed, for example, that the subscriber at substation A desires to connect with a subscriber in a distant exchange accessi lo by way of the exchange to which the trunk line comprising conductors 200 and 201 ere tends. Vfhen the receiv r is removed at substation A, a circuit is completed over the line conductors 11 and 12 for the line relay 1% of the line switch C. Upon energizing, the line relay 1% completes a circuit extend ing through the switching relay 13 the stepping magnet 21 in series to battery. This circuit is completed at armature- 20 of the line relay, and at armature 19 the test wiper 32 is connected to tie above circuit at a point midway between the switching relay and said stepping magnet. The operation now depends upon whether the test contact with wiich the test wiper 32 is in engagement is busy or not busy. If this test contact is busy, it will lave aground potential upon it, the switching relay 13 will be short circuited and the stepping magnet 21, which interrupts its own circuit, will be operated in the manner of a buzz-r to advance the switch wipers 30-33, inclusive, step by step in search of an idle trunk line, This operation will continue as long as the test wiper 32 continues to engage grounded or busy test contacts. However, we may assume that in the present case, when the call is initiated, the selector D is idle, and the test contact 36 therefore is not grounded. In these circumstances, when the line relay 14 is energized, the switch: relay 13 is energized immediately after wards, with the result that the line conduc tors 11 and 12 are disconnected from the line relay 1 1 and from ground, respectiwly, and are extended by way of armatures 15 and 18 and their working contacts, line wipers 30 and 33, trunk conductors 38 and -10, and armatures 60 and 63 and their resting contacts to the upper and lower windings, respectively, of the line relay 50 of the selector D.

Upon the extension of the calling line as above described, the line relay 50 will be energized over the line circuit and will clesev a circuit for the slow acting release relay 51. Upon energizing, relay 51 prepares the selector D for vertical operation in the usual manner, and also completes a holding circuit extending back to the line switch r) over the following path: grounded wo ing contact of armature 6 1 and said arma ture, conductor 39, test contact 36., test wiper 32, armature 17 and its working centact, winding 01" switching relay '13, and the winding of the stepping magnet 21 to bat tery. It is understood that the above circuit is established before the slow acting rclay 14; has had time to deenergize.

The calling subscriber may now operate his calling device in accordance with the first digit of the desired number. A series of'interruptions is thereby produced in the circuit of line relay 50, causing a corresponding series of deenergizations of the said relay which at each deenergization sends a current impulse through the slow acting relay 52 and the vertical magnet 56 to battery. By the operation of the vertical magnet 56, the switch shaft is raised step by step until the wipers 69-72, inclusive, stand opposite the bank level in which are terminated the trunk lines leading to the desired exchange. In the present case, the wipers will be raised opposite the level containing bank contacts 7346, inclusive. The slow acting relay 52 is energized in series with the vertical magnet, retaining its armatur, attracted throughout the vertical movement of the switch, and upon the closure of off normal contact springs 58, completes a circuit for the stepping relay 53. Upon energizing, relay 53 establishes a locking circuit for itself at its upper armature, and at the lower armature prepares a circuit for the rotary magnet 54. At the end ofthe vertical movement of the switch the slow acting relay 52 is deenergized and closes the circuit of the rotary magnet, which is thereupon energized to rotate the switch wipers into engagement with the first set of bank contacts in the level opposite which they were raised. The rotary magnet also breaks the locking circuit of the stepping relay 53, which, accordingly, is deenergized to break the circuit of the rotary magnet, which thereupon ceenergizes also, and again closes its interrupter contacts. The operation now depends upon whether the test contact with which the test wiper 71 is in engagement is busy or is not busy. If this test contact is busy it will have a ground potential upon it, and the stepping relay 53 will again be energized over a circuit which extends from the grounded test contact by way of the test wiper 71, armature 61 and its resting contact, off normal springs 58, interrupter contact'of the rotary magnet 5 1-, and the winding of the stepping relay 53 to battery. The stepping relay will, therefore, again close the circuit of the rotary magnet, which will operate to advance the switch wipers into engagement with the next set of bank contacts. This operation in which the stepping relay 53and the rotary magnet 54 are alternately energized and deenergized takes place very rapidly, and will continue as long as the test wiper 71 continuesto engage busy or grounded test contacts. In the present case, it will be assumed that the trunk line shown in the drawing is the first idle. trunk line, and when, therefore, the test wiper 71 arrives at test contact 7 1 and the rotary magnet 5% is deenergized, the stepping relay 555 will not a ain be ener izedz but the switching relay 55, which heretofore has been short circuited, will be energized by current flow over the following path: grounded conductor 89, winding of switching relay 55, oil normal springs 58, interrupter contacts of the magnet 54; and the winding of the stepping relay 53 to battery. Owing to the high resistance of the switching relay 55, the stepping relay 53 is not energized by current flow in the above circuit. Upon energizing, relay 55 disconnects the trunk conductors 38 and 40 from the windings of the line relay 50 and extends them by way of armatures and 63 and their working contacts, line wipers and 72, bank contacts 73 and 75, conductors 80 and 78, and normally closed contacts of reversing relay 100, to the upper and lower windings, respectively, of the double wound line relay 101 of the repeater R.

The line relay 101 is accordingly energized over the line circuit, and, upon attracting its armature 110, completes a circuit for the slow acting release relay102. Upon energizing, relay 102 at its armature 113, closes circuits through the polarizing winding of the electro-polarized relay 104 and slow acting relay 105, at its armature 112 prepares operating circuits for slow relays 103, 125, and vertical magnet 124:, which circuits will be later described, and at its armature 11 1 completes a holding circuit extending back to the selector D over the following path: grounded resting contact of armature 1 13 and the said armature, armature 123 and its working contact, working contact of armature 11 1 and the said armature, conductor 77, test contact 74, test wiper 71, and armature 61 and its working contact to the conductor 89, where it joins the previously described holding circuit extending back to the line switch C. The circuit just described serves to maintain relays 55 and 13 energized throughout the connection. As a further result of its energization, relay 102 closesv a bridge across the trunk conductors 200 and 201 which may be traced as follows: conductor 200, working contact of armature 115 and the said armature, armature 116 and its resting contact, upper winding of electropolarized relay 104:, normally closed contacts controlled by armature 109, right hand winding of impedance coil 107, and armature'133 of the now energized line relay 101 and its working contact to the trunk conductor 201. By the closure of the bridge just described, a circuit is completed for the line relay of the second selector in the distant exchange (not shown) in the usual man ner, and the said line relay and its associated slow acting release relay are accordingly energized and the distantselector is prepared for operation.

The calling subscriber may now operate nezzt digit in the desired number, thereby causing a series of deenergizations of the line relay 101 of the repeater R, which at each deenergization, opens the bridge across 'DhQ-tIUIllI conductors 200 and 201 and thereby interrupts the circuit of the line relay of the distant selector switch. The said selector is accordingly operated in the well known manner to raise its wipers in accordance with the digit called, after which the said wipers are rotated and connection is established with an idle trunk line extending to another selector switch. At the repeater R, while the line relay 101 is deenergizing intermittently to repeat impulses to the second selector switch in the distant exchange, it sends an impulse at each deenergization from grounded armature 110 and its resting contact, armature 112 and its w rking contact, to point 140 where the circuit divides, one branch extending to the winding of slow acting relay 103 to battery, and the other branch extending through armature 122 and its resting contact, off normal springs 137 and 139, winding of slow acting relay 125, and the winding of vertical magnet 124 to battery. The relays 103, 125, and magnet 124 are energized upon the first impulse, and the relays 108 and 125 being of the slow acting type, remain energized throughout the series of impulses. The relay 103, in operating, completes the bridge across trunk conductors 200 and 201 over a non-inductive path which may be traced from trunk conductor 200 by way of armature 115 and its working contact, armature 116 and its working contact, and armature 133 and its working contact to the trunk conductor 201. This operation, by re moving the windings of relay 104 and impedance coil 107 from the circuit, produces a better control circuit for operating the series of switches in the distant exchange. The operation of relay 125 prepares a new circuit for itself which is completed upon the first vertical movement of the switch, which causes the operating circuit for relay 125 and magnet 124 to be switched over tocontacts 137 and 138 of the off normal switch in well known manner. The vertical magnet 124 responds to each impulse of the series to position the wiper 130 opposite a desired level of its bank contacts, such as the level containing contact 136. At the end of the series of impulses, the slow acting relay 125 deenergizes and in so doing, switches the operating circuit trom the vertical magnet 12-4 to the rot magnet 127.

The calling subscriber may now call the third digit of the called number, with the result that another series of interruptions is produced in the circuit of line relay 101, which repeats impulses to the next selector of the series to effect selection of a trunk line leading to the exchange in which the called subscriber is located- At the same time, the line relay also repeats impulses over the previously pointed out path to the slow relay 120 and rotary magnet 127 of the switch S, causing its wiper 130 to be positioned on a bank contact, which contact is connected through a resistance to ground. At the end of the series of impulses, the slow relay 126 deenergizes, completing a circuit from ground, resistance 144, 140, or 141, depending, of course, on the series of impulses which positioned the switch S, to relay 106. Assuming the wiper 130 to be on bank contact 136, the circuit will'be completed from ground, resistance 144, bank contact 136, wiper 130, resting contact of armature 134 and the said armature,normally closed contacts controlled by armature 120, and the winding of relay 106 to battery- Relay 106, in operating, opens the operating circuit of the rotary magnet 127 at its armature 122, at its armature 120 completes a holding circuit for itself, and at armature 121 connects the wiper 130 with the conductor 163.

The calling subscriber may now call the remaining digits in the desired number, with the result that additional series of interruptions are produced in the circuit of the line relay 101, which operates as before to repeat the interruptions, and thereby brings about the operation of the switches in the terminating exchange which are required to complete the connect-ion with the called subscribers line. The bell at the called station is thereafter rung automatically, and when the called subscriber removes his receiver responsive thereto, the ringing equipment is automatically out 011, and the called station is supplied with talking battery through the windings of the back bridge relay of the connector in the usual manner. As is customary, this back bridge relay is provided with contact springs which reverse the connections of the incoming line conductors, thereby reversing the direction of current flow over conductors 200 and 201, and through the upper winding of the electro-polarized relay 104 at the repeater B. As a result, the relay 104, which heretofore has remained inoperative, is operated, and at its armature 118 closes a circuit through Belay 100. Relay 100 is a reversing relay which reverses the direction of current flow in the incoming trunk conductors 76 and 78, for no useful purpose, however, in connection with the apparatus shown; but inasmuch as it is a standard operation and is of utility under certain circumstances which it will not be necessary to mention, the circuits have been shown in this manner. Relay 100 also connects at its armature 109 the left hand winding of the impedance coil 107 in series with the right hand winding, with the object of increasing the efficiency of the talking circuit, at its armature 143 removes relay 42 looks itself up over the release trunk conductor in an obvious manner, and .at its armature 11 completes the meter operating circuit which may be traced as follows: from ground, resistance 14: 1, bank contact 136, wiper 130, resting contact of armature 13 1 and the said armature, working contact of armature 121 and the said armature, conductor 163, through the break contacts and winding of the thermostat T, conductor 7 9, bank contact 76, wiper 69, working contact of armature 41 .and the said armature, working contact of armature 16 and the said armature, Winding ot' meter magnet M to bat tery and ground.

The precise manner in which the metering operation take place will now be described. WVhen the metering circuit is closed, the call meter M is operated and is reoperated periodically thereafter at a rate determined by the amount of current flowing through the thermostat. This curren value is dependent upon the resistance included in the circuit by the positioning of wiper 130, which as has been previously described is positioned in accordance with certain digits oi the called number, and upon the class of the line calling. 7 1 1 {I5 The meter circuit and the circuit for the thermostat having been closed upon the called party answering will remain closed until the thermostat has heated up sufficiently to have its normal tension overcome by the magnet, at which time the circuit is interrupted, the meter magnet restores its armature in preparation for the next impulse, and the thermostat begins to cool off. As soon as it has cooled to a predetermined degree it releases itself from the influence of the magnet and again completes the meter and thermostat operating circuits. This operationis repeated throughout the period of conversation.

Since the line calling is not a party line it is provided with the resistance 9 connected in multiple with the meter winding which permits a maximum amount of current to flow through the thermostat winding. This causes the thermostat to heat up quickly, and therefore the meter is operated at the maximum speed.

Attention is called to the fact that while only two bank levels of the switch S have been shown, it is to be understood that in practice there will be the usual ten' levels. Furthermore, while one level is illustrated as having the same resistance associated with all bank contacts, it is to be understood that the resistance associated with each contact in the bank may be or a dilierent value, thus giving the thermostat T a wide selection or operating circuits in accordance with any of 100 exchanges to which the calling subscriber may have access.

When the conversation is finished, both subscribers will hang up their receivers. When the receiver is replaced at substation A, all the switches involved in the con nection are released and restored to normal, the release being initiated by relay 101 of the repeater R, Upon deenergizing, relay 101 opens the bridge across the trunk conductors 200 and 201, which causes the switches in the distant exchange to release in the usual. manner. The slow acting release relay 102 is also deenergized following the deenergization of relay 101, and breaks the holding circuit extending back over conductor 77 to the selector 1) and line switch 0.

As a result, relays 55 and 13 are deenergized and the said switches are restored to normal in the usual and well known manner. The relay 102 at its armature 112 and its resting contact also completes a circuit for the release magnet 125 of the switch S, causing the same to restore in well known manner.

All equipment has now restored to normal,

to party line subscribers, their rates are 're duced below those of the straight line sub scribers, the amount of reduction depending on the number of subscribers on the party line. The straight line meters (as shown) are-shunted by a resistance 9 which as previously described permits an additional amount of current to flow through the thermostat, causing the meter to be operated at a maximum speed. Now in equipping the two party line meters a higher resistance may be used, while in the case of the four party lines the resistance may be omitted, thus providing for three diflerent charging rates corresponding tothe three grades of service mentioned. In case a subscriber uses 7 different grades of service to which the subscribers are entitled as well as in accordance with the destination of the calls.

Party line meters suitable for use in the same system with the individual line meter shown, and controllable without charge by the circuits illustrated herein, are describedin Patent No. 1,486,900, issued to Emil J acobsen, March 18, 1924'. V

In cases where all calling lines are of the same class, or where it is desired that the meters be operated at the same rate regardless of whether the line in use is a party or straight line, the meter control circuits may be readily modified in such a manner that a local operating circuit is provided for the meter This permits a greater variation of the resistance values used in the bank contacts of the switch S, permitting a greater maximum value o t current to flow, and a resultant greater range in the rate of operation of the thermostat. This is especially desirable if the exchanges or offices are widely separated. To modify the circuits it is only necessary to connect the conductor 79 to conductor 16% instead of to the thermostat winding, and to connect the thermostat winding to spring .160 of relay 100 as illustrated in. Fig. 2 Now when relay 100 becomes energized it permits the operation of the relay 4-2 of the selector D in the same manner as previously described to complete the local operating circuit for the meter M, and in addition closes. an operating circuit for the thermostat at its armature 162.

l/Vhile this application illustrates the invention as ,used in a system wherein there are a large number of ofiices, it may equally well be applied to a system having ten or even a smaller number of oilices. In such a system the switch S, and relay 106 may be entirely dispensed with, in which case the thermostat will be inserted in the meter conductor of the selector D as illustrated in Fig. 1 Each level of bank contact-s such as 76 of the selector will have all its contacts tied together, and the whole will be connected to a resistance value in accordance with the rateof charge to be made for connection to the exchange reached over that level. Oi course as is well known the switch D having ten levels permits the connection of ten different resistance values in accord ance with difierent rates to be charged for connections with the ten exchanges in the system.

Having described the invention, what is to be considered new and desired to have protected by Letters Patent will be pointed out in the appended claims. I

What I claim is: w 1. In a telephone system, calling lines of different classes independent or" their location, meters for said lines, a plurality of exchanges, a trunk line accessible to said calling lines for extending connections to called lines in any of said exchanges, means for completing a. meter operating circuit for the calling line when a connection has been es tablished, and means operative to interrupt said circuit periodically at a rate dependent jointly upon the exchange in which the pan ticular station called is located and upon the class of the line calling.

2. In a telephone system, a line, a meter for said line, automatic switches for extending connections from said line to called lines, said switches responsive to series of impulses transmitted over the said line, meansoperated by certain of said series of impulses for determining the amount of current which will be permitted to flow through said meter at any period when a talking connection has been established, and thermostatic device included in the meter circuit operative to periodically open and close said circuit at intervals dependent on the amountof current flowing.

3. in a telephone system, a line, a meter -for said line, a trunk line, automatic switches for extending connections over said t Link from said first line to called line-s, means op= erable when a call is answered for causing a flow of current through said meter, and means operated in response to such current flow for periodically interrupting the current flow through said meter while the con nection is maintained.

4;. In a telephone system, a calling line, a meter for .aid line, a trunk line, automatic switches for extending a connection over said trunk from said calling line to a called line, means operable when the call is answered to cause a current fl w through said meter, m ans associated with said. trunk for determining the current tlow in accordance with the location of the called line, and means op crable to periodically interrupt the current flow in said meter at a rate dependent on the amount of current flowing therethrough.

5. In a telephone system, a line, a meter for said line, trunk lines, automatic switches for extending the line over said trunk lines to called lines, another switch operable simultaneously with certain of said automatic switches for selecting an operating circuit for said meter, and means included in the selected operating ircui-t and operated by the current flowing therein, for period ically interrupting the same at a rate determined by the operating circuit selected,

6. In a measured service telephone system in which the subscribers are graded according to the class of service to whic h'they are entitled, automatic means for always assess ing charges against calling l-ines at a rate depending on the particular connection set up, and means associated with other classes of calling lines for changing the opeiating rate of said last means in all connections set up in accordance with the grade of service the subscriber calling is entitled to.

7 In a measured service telephone system in which the subscribers are graded according to service furnished, automatic means for assessing var ing char es against a callu v D O ing line depending on the grade of service the subscriber is entitled to, the distance from the calling to the called subscriber, and the duration of conversation.

8. In a measured service telephone system in which the subscribers are graded according to service furnished, automatic means "for assessing charges against a calling line depending on the grade of service the subscriber is entitled to, the location of: the called subscriber and the location of the call ing subscriber.

9. In a measured service telephone system in which the lines are provided with meters, circuits for said meters, a heat operated interrupter device included in said circuit with the meter of a calling line to operate the same periodically.

10. In a measured service telephone systemin which the subscribersare graded according to service furnished, a heat operated device for assessing charges against a calling line in accordance with the grade of service to which the subscriber is entitled.

11. In a measured service telephone system in which the lines are provided with meters, said system comprising means for closing the meter circuit or" a calling line when the called subscriber answers, and a thermostatic device included in said meter circuit to interrupt the same periodically.

12. In a measured service telephone system in which the lines are provided with meters, said system comprising means for closing the meter circuit of a calling line when the called subscriber answers, means ,IOI varying the resistance of said circuit in accordance wlth the locatlon of the called line, and a thermostatic device in said circuit operable to interrupt the same at a rate proportionate to its resistance.

13. In a telephone system, a pair of calling lines, a meter for each line, a meter controlling device common to said meters, said device operated to interrupt the circuit of the meter with which it is associated to assess charges thereon, and means associated with one of said meters for causing said device to operate at difi'erent rate of speed.

I l. In a telephone system, subscribers lines arranged in two diilerent classes, a high rate and a low rate class, means for extending connections from said lines, means for automatically assessing varying charges on calling line dependent upon the value of the extended connection, and additional means for varying said charges when the calling line is of the high rate class.

15. In a measured service telephone system, subscribers lines, certain of said lines arranged to be charged at a lower rate than other lines regardless of the line called, and automatic means for assessing charges against a line of either class in accordance with the value 01": the connection extended therefrom.

16. In a measured service telephone sys tem, a plurality of calling lines of different classes, meters for said lines, a meter controlling device common to said lines, means for setting up connections from any calling line to a called line, means for causing said meter controlling device to operate at a speed dependent on the line called, and means associated with the meter of acertain one of said lines for causing the meter controlling device to operate at a different rate.

17. In a measured service telephone system, lines, meters for said lines, a meter controlling device common to said lines, means for setting up connections to called lines,

means for causing said meter controlling device to operate the meter of a line calling at a rate dependent on the line called, and means associated with the meters of certain lines for altering the rate of operation of said meter controlling device regardless of the line called.

In witness whereof, I hereunto subscribe my name this 26th day of December, A. D., 1922.

VANCE E. HOFFMAN.

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