US1901177A - Multioffice telephone system - Google Patents

Description

March 14, 1933. o. c. LEVY 1,901,177

MULTIOFFICE TELEPHONE SYSTEM Filed March 31, 1952 2 Sheets-Sheet l TRK f |||||n| mums '6 13 Q I {gjuumla lllilllll a i 5 IIHIIILT llllllilil i Pi k: a MW; Q

@maiml Hiflilli sue OFFICE- March 14, 1933. O. c. LEVY 1,901,177

MULTIOFFICE TELEPHONE SYSTEM Filed March 31, 1932 2 Sheets-Sheet 2 SANKS n l l l Inuen D [:lscar' [3.LEL

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Patented Mar. 14, 1933 s mange t file so whim? osoi a of tsvir, or onions-o, ILLINOIS, hesitation, BY risers-manure; ro AS- SOGIATED :snscrnrc inc, or onrcsso, ELLIIG'OIS, A oonroaerron or DELAWARE MULTIOFFICE TELEPHONE SYSTEM Application filed March 31, 1932. Serial No. 603,124.

This invention relates to telephone systems in general, particularly to multi-oiiice telephone systems which include satellite or suboflices and in which connections are completed through the medium of automatic switches. The invention has for its obj ect the provision of new and improved circuits and apparatus for interconnecting the various oiiices in such systems to provide reliable and eiiicient local,

and auxiliary services.

In systems of the above type, the toll ant. auxiliary service switchhoards are usually located at one of the main oilices, and special service calls from all oilices of the system are e tended thereto. The special service traiiic may be routed over the same inter-office trunks as the regular interoiiice traiiic accordingto the arrangement shown in the copendingapplication of V. S. Tharp, Serial No. 489,530, filed July 21, 19-30, or a separate group of trunks may be provided for each class of traffic. In either case, the trunks over which the special service traflic is han= died will require provisions for the so-called G. L. R. toll service as a large percentage of the toll traiiic is handled. on this basis in prcsenhday practice. i

If the regular interofiice traffic is heavy and w the trunkgroups are accordingly large, it is often more economical to provide a separate trunk group for the special service trafiic than to equip the regular trunks for this service.

In case a satellite or sub-oflice is involved, the trunk arr ngement must take into considera ion the maintenance of uniform numbering throughout the system. Further, there must be no interierence between the special service co le numl'iers and the numbers assigned to subscribers stations even though both numbers utilize certain common.

The present invention provides a simple and cfticient trunking; org'anizationior use digits in under the above conditions. The trunking layout itseli constitutes one feature hi the invention and an improved selector repeater, which makes this layout possible, COILMITUCGS another feature. These features, and others not spec fically mentioned. will as described hereinafter 111 connection with the detailed description of the system embodying the invention, which is shown in the accompanying drawings, of which Fig. 1 shows diagrammatically a part of the trunking layout oi a main oi'iice and an interconnected sub-oliice. Fig. 2 shows circuits oi equipment located at the sub-ofice.

Referring now to Fig. 1,'the equipment located to the left oi the'broken line is located in the sub-oiiice, and that located to the right oi the broken line is located in the main oilice. The subcliice subscribers linesterminate in lineswitches LS, which have access to switching-selector repeaters The selector repeaters have access by way of their banks to trunks extending to local third selectors S and over the firstlevelof their banks to trunksTl, which terminate in incoming special second selectors at the main office. Associated WlthBfiCh selector repeater is the usual secondary lineswitch SLS which has access to trunks T extending to incoming selectors at the main oifice. The sub-oifice selectors, such as S, have access to local connectors C, and these in turn have access to the s'ub-ofiice subscribers lines. understood, of course, that trunking equipment is provided for incoming" calls from the main oilice, but since this forms no part of the invention it has been omitted in the drawings.

In the main office, subscribers lines terminate in lines-witches LS1 which have access to first selectors 18. As previously stated, the trunks from the sub-office terminate in incoming selectors 18. The banks of the incoming selectors are multipled with the banks of the main oilice first selectors on all levels except the first. The first level of the banks of the incoming selectors is unequipped and the corresponding level of the main office first selectors terminates in trunks extending tothe special second selectors 82S. The special service trunks from the first level of the It will be multipled on all levels except the first with the banks of the local first selectors. and incoming selectors of the main oilice. The special selectors have access by way of the first level to trunks extending to special third selectors 83S and these in turn have access over various levels to the special service trunks. The combined line and recording trun CLR, accessible in the tentn level of the special third'selectors, has been shown by way of illustration. 7 The first selectors and incoming selectors on the various multipled levels have access to local second selectors 2S, and these in turn to local third selectors 38. The third selectors have access to the various groups of connectors, including the group represented by connector 6, which in turn have access tothe main office subscribers lines.

The system shown is of the five-digit or 100,000-1ine type. A total of twothousand numbers have been assigned for sub-office A and lineswitch LS may be of the usual type in use in automatic telephone systems. Selector repeater SSR is the usual type of Fatrowger switch provided with a fourth Wiper for switching purposes in addition to the usual line and test wipers. Associated with the selector repeater is a secondary lineswitch SLS which-has access to the trunks, such as T, extending to the main office. The banks of the selector repeater, part of which are shown in the drawings-consist of a 200+ contact line bank and a 200- contact test bank. The upper contacts of the first set in each level of the test banks are wiredin a manner to permit the switch to select the proper route over which the call is to be extended. In the-line bank,the first level is assigned to trunks T1, which extend to incoming spe cial second selectors at the main oflice, and the third and fourth levels are assigned to trunks extending to local third selectors in the subofiice. The remaining levels of this bank are unequipped.

WVith the foregoing brief description in mind, the operation of the selector repeater and associated equipment in various calls will now be described indetail. sumed that the subscriber at substation A has initiated a call and thatlineswitch LS has extended the calling line tothe trunk comprising conductors 1214, which terminates in switching-selector repeater SSE. Line relay 4 operates over a circuit which includes trunkconductors 12 and 1%, contacts 15 and It may be asbe described subsequently. Relay 5 operates,

prepares the impulsing circuit at contacts 35, connects ground'to release trunk conductor 13 and to the lower winding of polarized relay T at contacts 36, and at contacts 37 completes a circuit for relay 2 and applies ground to holding conductor 68 which extends to the secondary lineswitch. Relay 2 operates, prepares the metering circuit at contacts 22, and completes a holding circuit for itself at contacts 23. Polarized relay 7 does not operate at this time. I

Referring now to the secondary lineswitch, relay 7 3 operates over the circuit prepared by relay l, which may be traced from ground, winding of relay 7 3, contacts 81, conductor 6?, contacts 33, upper winding of polarized relay 7, resistance 71, conductor 66, contacts 75, resistance 95, and contacts 94, to battery. This circuit is completed only in case an idle outgoing trunk is available, which is assumed to be the case at this time. Relay 73, accordingly, operates and completes a test circuit at contacts 84:. In case the Wipersare standing on the contacts associated with a trunk which is engaged in a connection, wiper 88 finds ground on the test contacts of the trunk, and this ground by way of contacts 77, 84, and 86 energizes stepping magnet SM of the lineswitch. Relay 72 is shunted by the ground on the testcontact and does not operate. The stepping magnet on operating opens its own circuit at contacts 86, and on deenergizing advances the wipers one step to the next set of contacts. This operation is repeated until an idle trunk is found, for example the trunk T, whose idle condition is indicated by the absence of ground on the test contact. Relay 7 2, accordingly, operates from ground on the holding conductor 68, contacts 86, winding of the stepping magnet, to battery. The stepping magnet does not operate due to the high resistance of the relay. Relay 72 opens the test circuit at contacts 77, and completes a holding circuit for relay 73 at contacts 78. The initial operating circuit of relay 73 is opened at contacts 7 5 and 81, and line conductors 66 and 67 are connected through by way of contacts 76 and 80, contacts 82 and 85, and wipers 87 and 90, to the conductors of the seized trunk. Relay 72 also completes a circuit for trunk relay 74; by way of contacts 79 and wiper 89. Relay 7 4 on operating applies ground to thetest contact of the trunk at contacts 92, and at contacts 91 closes a point in thechain circuit for relay 93.

If all outgoing trunks are engaged at the time the call is initiated, all of the trunk reated and the chain circuit of relay 93 will be completed. Relay 93 will be energized and battery will be removed from the starting circuit of all idle secondary lineswitches by the opening of contacts 94; Accordingly, a call initiated under these conditions wil not be extended to the main office. In this case, however, it is desirable to permit the subscrib- 'er to dial suflicient digits to indicate the zone ofthe call. The calling subscriber will, therefore, be given a dial tone, which will notify him that the apparatus is in condition to receive the dial impulses. The circuit for the tone extends over contacts 51 and 43, conductor 69, contacts 83 and 76, conductor 66, con. tacts 38, through the upper talking condenser of the selector repeater, to the upper line conductor of the calling line. If the subscriber dials the number of a station connected to the sub-exchange, the main oilice branch extending to the secondary lineswitchwill be disconnected and the connection will be completed over the wipers of the selector repeater, as will be explained subsequently. However, if the number dialled indicates a main o'tlice call the wipers of the selector repeater wil. be held in an off-nor1nal position, and relay ,8 of the selector repeater will substitute busy tone for the dial tone by opening contacts 43 and closing contacts 44. v The subscriber is then expected to release the connectionby hanging up his receiver. 7

Before proceeding with the description, it will be well to consider the various combinations of numbers which the subscriber may tor repeater will cease to function and the call will be extended over the seized main ofiice trunk. If the call is for the special service operator, the first digit will be 1, and in this case the connection will be switched over the wipers of the selector repeater, and the service connect-ion at the main exchange will be re leased immediately. 9

To resume the description, it will be assumed that the calling subscriber wishes to extend a connection to another sub-oflice subprepared for the receipt of impulses, we have the following operation upon the receipt of the first series of impulses: Relay 4 on deenergizing in response to each impulse of the calling device completes a circuit over contacts 31, 17, 35, and 56 for vertical magnet VM, and the latter raises the switch wipers step by step to the third level. Relay 6, which is connected in parallel with the vertical magnet, operates in response to the first impulse of the series, and, due to its slowreleasing characteristics, remains operated throughout the series of impulses. The upper winding of relay 7 and resistance 71 are short circuited by the closure of contacts :39 to -improve the transmission of impulses over the trunk to the main olhce. The impulses are repeated by relay 4 at contacts 33, and the incoming selector at the main office is raised to the third level simultaneously with the operation of the selector repeater. Relay 8 operates upon the first vertical step of the wipers of the selector repeater due to the closure of vertical oil-normal contacts 96.

Relay 9 now operates over acircuit which may be traced from ground at contacts 37, contacts 40, 98, 46, and 59, winding of the relay, to battery. Relay 9 on operating prepares the rotary magnet circuit ,atcontacts 49, at contacts 48 completes a holding circuit for itself which may be traced from battery, winding of the relay, contacts 5.9, 46, 98, 61, 48, 36, and 26, to ground. Shortly after the last impulse of the series, re1ay6 restores and completes a circuit by way of contacts 41 and 49 for rotary magnet RM. The rotary magnet energizes and stepsthe wipers in on the first set of contacts of the banks of the called level and openstheholding circuit of relay 9 at contacts 61. Relay 9 restores and opens the rotary magnet circuit at contacts 49. As soon as. the wipers engage the bank contacts, a circuit is completed from ground, contacts 26, 36, and 54, upper contact of the test bank, wiper 62, winding of relay 11, to battery. Relay 11 operates, opens the vertical magnet circuit at contacts '56, completes a circuit for the release magnet at contacts 57, closes the circuit for the upper winding of relay 10 at contacts 58, which circuit is of no utility in the present instance, opens the circuit of relay 9 at contacts 59, and .opensthe circuit of the test wiper 63 at contacts 60. It will be noted that the closure of contacts '58 completes a circuit by way of the upper winding of relay 10, contacts 52, winding of release magnet, to battery; and thata parallel circuit is completed over contacts and 57,- Relay 10 accordingly is short circuited and does not operate, but the release magnet does operate and restores the wipers of the switch to normal. A locking circuit is completed for the release magnet atcontacts to insure its continued energization-after the wipers leave the bank and start to restore vertically. Upon the switch wipers reaching normal position, relay 8 opens the circuitof the release magnet at contacts 45. The opening of these contacts also removes the short circuit from the upper winding of relay :10,

LID

in series with the release magnet by opening'contacts 52, opens the dial tone circuit at ;contacts 51, and prepares various other circuits which will be described in more detail in later paragraphs.

The subscriber now dials the second digit of the called number, which is also the digit 3, and the wipers of the selector repeater are again raised to the third level and stepped in on the first setof contacts. The impulses are repeated over the trunk to the main office as in the previous case and serve to operate a second selector to which the incoming selector has extended the connection responsive to the firstdigit dialled. Since relay 10 is operated, wiper 62 will not find ground on the upper test contacts and consequently relay'll is not operated. The selector now proceeds to test for an idle trunk in the called level. Assuming that the first trunk in. the level is engaged, wiper 63 will find ground on the lower test contact, which ground by wayof contacts 60, 19, 55. 61, 98, $6, and 59 will operate relay 9. Relay 9 completes the rotary magnet circuit at contacts 19 and the .wipers are accordingly advanced another step. Subsequent trunks are tested in. the

same manner until an idle trunk is found which is characterized by the absence of ground from the test contact. Relay 1 now operates from ground by way of contacts 26 V and 36. winding of the relay, contacts 55, 61,

98,46,'and 59, Winding of relay 9, to battery. Relay 9 does not operatedue to the high resistance of relay 1. Relay 1 disconnects the incomingtrunk conductors 12 and 14 from the line relay of the selector repeater at contacts 15 and 21 and extends them by way of contacts 16 and 20 and wipers 6 1 and to the local trunkextending to the local third selector. The line relay of the succeeding switch operates in the usual manner and ground is returned on the release trunk conductor which is switched over at .contacts 18 to the upper terminal of relay 1. This ground holds relay'l and the switching relay of the preceding line switch in operated position. Relays 4 and 5 restore, the former opening the loop circuit originally extended over the trunk to the main ofiice, thereby releasing the switches in the main office.

Ground is removed from conductor 68 upon the release otrelay 5,thereby permitting relays 72 and 73 of the'lineswitch to restore to normal and release the main oilice trunk. Further impulses serve to operate the sucice code numbers.

ceeding local selector and connector in the usual manner and extend the call to the called subscriber.

In case the second digit of the called numis opened at contacts 54. It will thus appear fromthe foregoing explanation that the-operations involved in setting up a connection of the type described is substantially the same as for the ordinary switching-selector repeater.

Calls from the sub-ofice to main ofice stations, such as station A3, involve the calling of a number whose first digit is the same as the first digit of the'sub-ofiice subscribers numbers and whose second digit corresponds to the first and second digits of special-serv- The operation of the selector-repeater in responseto the first digit is exactly the same as previously described for a local call. In response to the second digit, i. e.,- the digit 1, the wipers of the switch are raised to the first level and r0- tated tot-he first set of contacts in this level as before. Since relay 10 was operated in response to the first digit, wiper-62 will find ground on the upper test contact by way of contact-s 53, 36, and 26,.and relay 11 will accordingly operate. The'closure of the circuit for the upper winding of relay 10 is without efiect, as this relay is now held operated over its lower winding, and the circuit of the release magnet is open at contracts 52. Relay 11,'however, disconnects the vertical magnet at contacts 56 and opens the test wiper circuit at contacts 60 and the selector repeater remains at rest upon the first set of contacts of the first level throughout the rest of the call. The wipers standing on these bank contacts do not interfere with the extension of calls over the trunk as the line wipers are disconnected at 00h tact- s 16 and 20 and the test wiper is disconnected at contacts 60. Subsequent impulses are repeated over the trunk as beforeand serve to operate the remainder of the switch train at the main ofice and extend tie connection to the called line therein.

When the called subscriber responds, the connector reverses battery over the trunk in the usual manner andrelay 7 of the selector repeater operates due to its two windings assisting each other. Relay 7 connects relay 3 in series across the outgoing trunk by closing.

contacts 42 and opening contacts 100. Relay 3 operates, completes another point in the metering circuit at contacts 27, opens the circuit of relay'2 at contacts 28 and reverses the connection or" the calling line to theline relay or" the selector repeater by opening contacts 24' and 30 and 'closing'contacts 25 and 29. 'Metermg or booster battery is applied to the release trunk of the calling line over the lead MB, resistance R, contacts 23, 27 36, and conductor 13. This application of metering current is only momentary as relay 2 restores after a short interval and opens the metering circuit at contacts 22. The opening of contacts 23 prevents the reoperation of relay 2, and consequently prevents the reoperation of'nthe meter during the remainder of the When the calling subscriber hangs up at the termination of the call, relay 4 releases, followed by the release of relay 5. A circuit is closed for the release magnet via contacts 31, 17, 34, 10], and the magnet operates to restore the switch wipers to normal position. Relay 8 releases following the restoration of the wipers, and the remainder of the relays deenergize and release due to the opening of contacts 36 and 37. The opening of the loop to the main oflice permits the switches therein to release in the usual way.

A call from a sub-oflice subscriber to amain oilice subscriber whose number begins with some other digit than the digit3will now be considered. The sub-ofiice equipment oper ates as. in the previously described connection responsive to the initiation of the call.

digit 5, and the calling subscriber dials this digit, the wipers-of the selector repeater are raised to the fifth level and step in on the first set of contacts inthev same manner described for previous calls. The series of impulses is also repeated over the trunk to the main office and operates the incoming selector in that otfice to the fifth level, in which an idle trunk to a second selector is selected. Upon engag- 0 ing the first set of contacts, test wipers 62 of the selector repeater finds ground through resistance R1. Relay 11 operates in a circuit including the test wiper and the resistance and completes the various circuits described 5 for previous connections. It will be recalled that relay 11 upon operating connects the release magnet of the selector repeater in parallel with itself and also completes a circuit for the release magnet and the upper winding of 0 relay in series. In the present connection the release magnet does not operate at this time due to the inclusion of resistance R1 in the circuit. This resistance also is of such value that relay 10 is enabled to operate in se- 5 ries with the release magnet and lock up over its lower winding. Relay 10, of course,

opens the release magnet circuit at contacts 52 and completes various other circuits as before. The subscriber then dials the remain- 0 ing digits of the called number which are repeated over the trunk to, the main ofiice in the usual manner but do not operate the selector repeater further. The selector repeater accordingly remains, throughout the 65 call, in the position to which it was operated by the first digit.

Assumingthat the number called begins with r When the calling subscriber hangs up, re-

lays 4t and 5 release and permit the selectorrepeater to release in the usual manner. The

opening of the loop circuit over the. trunk to the main office permits the main oifice switches to restore as usual.

The operations involved in establishing a case, the selector repeater is prepared for operation and the branch connection is extended to the main ofiice as described in previous connections. The subscriber then dials the first digit,that is, the digit 1, and line relay 4 of the selector repeater transmits a single impulse to the vertical magnet of the switch,

which raises the wipers Opposite the first level of bank contacts. Relay 6 operates in parallel with the vertical magnet and, upon the operation of the ofi'-normal relay 8, completes a circuit for stepping relay 9. Relay 6 releases shortly after the impulse and completes the rotary magnet circuit which'is prepared by relay 9, and the magnet steps the wipers in on the first set of bank contacts. On operating the selector repeater to the first level, normal post springs NPS operate to close contacts 99, thereby "completing a circuit for test wiper 63, independent of contacts 55 of relay 10. This prepares the selector repeater for testing the trunk in the first level without first requiring the operation of relay 10 as was the case on calls to local subscribers in the sub-ofiice. The trunks are accordingly tested in the usual manner and when an idle one is found the absence of ground on the contactengaged by wiper 1 63 permits relay 1 to operate in series. with relay 9. The calling line accordingly is dis-i connected from the line relay of the selector repeater at contacts and 21, and at contacts 16 and 20 is connected through wipers 64 and 65 to the talking conductors of the trunk extending to the main olfice from the first level of the selector repeater banks. As previously stated, these trunks terminate in incoming special second selectors at the main oflice whose banks are multipled with the local special second selectors at that office. The branch connection to the main oflice is released following the operation of relay 1 and the consequent release of relays 4L and 5. The subscriber then dials the second digit ofthe special service code, again. the digit 1, and the incoming special second selector is operated to the first level in which a trunk to a special third selector is selected. The third digit, which may be the digit 0 for example, in case the call is for the toll recording-completing operator, will operate the special third selector to the tenth level, and an idle trunk in that level will be selected. The

i the main oflice via an idle trunk in one of said a sub-office, two groups of trunks connect-' ing the oifices, local trunks in the sub-oflice, a selector repeater in the sub-ofiice for extending local or outgoing calls, means in the selector repeater for preliminarily routing all calls to the main oflice via an idle trunk in one of said groups, means responsive to the receipt of an impulse series of a particular value for switching the call from the trunk in said one group to an idle trunk in the other of said groups, and means responsive to the receipt of a pluralityof impulse series of particular values for switching the call from the trunk in said one group to an idle one of the local trunks.

2. In a telephone system, a main oflice and a sub-oflice, two groups of trunks connecting the ofices, local trunks in the sub-office, a selector repeater equipped with a set of wipers, means associated with the selector repeater for preliminarily routing all calls to groups and independent of said wipers, and means for operating the selector repeater to switch a call to either an idle trunk in the other of said groups-or to an idle one of the local trunks via said wipers.

3. In a telephone system, a main olfice and a sub-office, two groups of trunks connecting the offices, local trunks in the sub-oflice, a selector repeater equipped with a set of wipers,'means associated with the selector repeater for preliminarily"routing all calls'to the main oii icewvi'a an idle trunk in one of said groups and independent of said wipers,

' means for transmitting digit impulses to the selector repeater to determine the ultimate routing of a call, means in the selector repeater responsive to the receipt of a digit of a partlcular value for releasing the trunk in said one group and for extending the call to the main office via said wipers and an idle trunk in the other of said groups, and means the selector repeater responsive to the receipt of aplurality of digits of particular values for releasing the trunk in said one group and for extending the call via said wipers to an idle local trunk.

4. In a telephone system, a main ofiice and a sub-office, subscribers lines terminating in each ofl'ice, an operators switchboard in the main office, two groups of trunks connecting the offices, a selector repeater at the sub-office,

means responsive to the initiation of a call by a sub-oilice subscriber for connecting the subscribers line 'to the selector repeater, means associated with the selector repeater for preliminarily extending a connection. to

the main office, subscriber-controlled means for transmitting digit impulses to determine the ultimate routing of the call, meansre' sponsive to digits indicatinga call to a main ofiice subscriber for disabling the selector repeater and for completing the connection over the trunk engaged initially, means responsive to digits indicating a call to a sub olhce subscriber for releasing the initially en} gaged trunk and for completing the connec tion through the selector repeater, and means responsive to digits indicatingja call to said switchboard for releasing the initially engaged trunk and for completing the connec-' tion through the selector repeater and over an idle trunk in the other of said groups.

t 5'. In a telephone system, an automatic switch having wipers, a contact bank com.- prising a plurality of levels accessible to said wipers, outlets terminating infthe contacts of certain levels, an auxiliary switch associated with said first switch, other outlets accessible to said auxiliary switch, means for seizing said first switchand for transmitting thereto a plurality of series of impulses in ac cordance with the digits of a called number,"

means responsive to the seizure ofthe switch for operatingthe auxiliary switchto extend a connection over an idle outlet accessible thereto, means responsive to the first series of impulses for raising the wipers of the first switch to a level corresponding to the digit represented by the impulse series and for simultaneously repeating theimpulses over' the connection established via said auxiliary switch, means responsive to the initial operation of the switchwipers to a certain level V for restoring the wipers tonormal and for rendering them reoperable responsive to the next series of impulses received, means re sponsive to the initial operation of the switch wipers to a different level for maintaining the same in operated position while a connection is completed via the auxiliary switch, and means responsive to the initial operation of the switch Wipers to a still dilierent level for causing the wipers to be moved over the level in search of an idle outlet accessible ting of the switch for completing a circuit for said stepping relay independent of said second relay.

7 In a telephone system, a two-motion switch, primary and secondary magnets for the switch, a stepping relay for controlling the secondary magnet, a second relay, a Wiper for the switch, means for operating said primary magnet to set the switch, means responsive to a particular setting of the switch for operating said second relay to connect the stepping relay to said wiper, and means responsive to a different setting of the switch for connecting the stepping relay to said wiper independent of said second relay.

8. In a telephone system, a two-motion switch, primary and secondary magnets for the switch, a relay for controlling said secon dary magnet, a second relay, a wiper for the switch, means for operating the primary magnet to set the switch, means responsive to a particular setting of the switch for operating said second relay and for releasing the switch, contacts operatedv by said second relay for connecting the first relay to said wiper, and means responsive to a different setting of the switch for connecting the first relay to said wiper without releasing the switch.

9. In a telephone system, a two-motion switch, primary and secondary magnets for the switch, a test wiper for the switch, a stepping relay and a control relay, means for operating the primary magnet to set the switch, means responsive to a particular set ting of the switch for operating said control relay and for releasing the switch, contacts on said control relay for rendering said step ping relay effective to control said secondary magnet after the primary magnet is reoperated to reset the switch, and contacts closed mechanically responsive to a particular initial setting of the switch for short circuiting the contacts of said control relay whereby said stepping relay is rendered effective to control the secondary magnet without releasing and resetting the switch.

10. In a telephone system, a selector repeater, wipers for the selector repeater, contacts disposed in a plurality of rows accessible to said wipers, circuit connections for normally connecting switching potential to contacts in certain of said rows, other circuit connections normally ineffective for connecting switching potential to a contact in a different one of said rows, means forv operating the selector repeater to set the wipers on contacts in one of said certain rows, and means responsive to said wipers engaging a contact therein for rendering said first circuit connections inefi'ective and for rendering said other circuit connections effective.

11. In a telephone system, a selector repeater, wipers for the selector repeater adapted to engage contacts in a plurality of levels, circuit connections to contacts in certain of said levels normally marking such levels as switching levels, other circuit connections to a contact in a difierent level for marking that level as a switching level, and means responsive to a preliminary setting of the selector repeater wipers to a contact in one of said switching levels for rendering said other circuit connections eiiective. I

12. In a telephone system, a selector repeater, a wiper for the selector repeater, two contacts accessible to said wiper, conductors eX- tending from said contacts to the selector repeater, means in the selector repeater for connecting a potential to one of said conductors when the selector repeater is taken into use, means for operating the selector repeater to set its wiper on the contact to which said one conductor is connected, and means responsive to the wiper engaging said contact for disconnecting the potential from said one conductor and for connecting it to the other conductor.

In witness whereof, I hereunto subscribe my name this 25th day of March, 1932.

OSCAR C. LEVY.

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