US1784698A - Telephone system - Google Patents

Description

DCC. 9, F. MERK I TELEPHONE SYSTEM Filed Dec. 3. 1927 2 Sheets-Sheet l al 'U Dec. 9, 1930. MERK 1,784,698

N1. E LL- i k l n "D nr) E| N Patented Dec. 9, 1930 Y UNITED STATES FREDRIGH MERK, FFRANKFORT-ON-THE-MAIN, GERMANY TELEPHONE sYstLnivr` Applicationv filed December 3, 1927,v Serial No. 237,556, and in Germany December 4, -1926. Y

l This invention relates to improvements in automatic telephone exchanges, and more particularly to the so-called connectors used in public telephone systems for establishing l the so-called long distance or toll line connections, the same connectors being'applicable likewise for local calls and upon correspondingly changing` the circuit arrangements also for ordinary and preferred local 10 connections. i*

F or long-distance or toll-connections as distinguished from local connections, the following special conditions are in question (l) Local connections'are to be broken to favor a toll call after a preliminary warning has irst been given to the` speaking subscribers on the local line.

(2) Subscriber lines already busy with a toll call Vare to be closed'to local and other toll calls.

(3) The toll operator must be advised by signals whether or not a line called is free or busywitha localy or toll call.

(4) The connections of localv subscribers to the toll'exchange must be such that the subscribers can give flash signals to the toll opera-tor, by joggingthe receiver hook, while the toll operator must able to repeat bell calls to a subscriber who `may prematurely hang up his receiver after answering the first call.

lt is to be assumed that the connectors are provided (as usual) with a three-wired multiple contact bank and that the subscribers lines have been connected to this contact bank without intermediate interruption points.

Heretofore it was assumed that these conditions could best be satisfied by preliminarily preparing the toll-conn`ections by adjusting the final selectors and subsequently closing the talking circuitfbya switching operation by the toll operator, independently of the adjusting movement of said selectors.V vHowever, the introduction of this arrangement to practice has led to such very complicated and expensive selector arrangements that it is preferred (for economical reasons) in most of the larger exchange systems, to e'ect'toll` l connections by means of manually operated e0 tall-beards, while in smallerstations (such.

sub-stations vand rural or landsstations) in which operators cannot be present continu ously, disconnection by the toll exchange has not been used.

According to thepresent invention, the selectors are'controlled andthe connections for toll calls are eectedby a single continuous operation (in a similar manner to local connections) in such a manner that in both cases the switching operations following the setting of the selector are always made automatically immediately after the setting operation.

The object of this combination of the operations in the `final selectors orconnectors, both i for local calls and toll calls, is to utilize the same switching means inl both cases. According to the arrangement in use heretofore, the switching means which come Ainto operation automatically in the case of local calls, after the final selectorshave been set to ascertain whether the called subscribers line is free or busy with a local call, for locking the lines and for ringing up the subscribers must be rendered inoperative and replaced by other switching means controlled by thetoll operator, whereas the `arrangement according to the present invention makes it possible to use v the same 'automatic connectors even for tollconnections, these arrangements being made dependent on atoll testing and locking relay for toll-connections. 'Y i The main object of the present invention is to so simplify the linal selectors or connectors for the toll traffic that although the same selector switches are used, it is possible to break the localconnection at the toll exchange when toll calls `are received. The control of the nal selectors is also simplified in such manner that it may be effected by the toll operator without any difficulties. rloll-connections are eiected by the toll operator in the same manner as local connections by simply selecting the wanted subscribers number without any further additional switching operation.

A particular' advantage of the invention resides in the `fact that Vit is unnecessary to preliminarily busyl the Selector switches and connecting ortrunk. lines for a long time,

as has heretofore been the case in initiating or establishing toll calls.

A further advantage of the present invention over prior arrangements resides in the fact that it entirely fulfills the aforementioned conditions, whereas the conditions are only partly fulfilled by the prior art arrangements.'

The invention will now be described withreference to the accompanying drawings showing diagr'ammatically an embodiment of the invention, wherein Fig. l shows in a system embodying' `|he invention, the position of a tolloperator with an incoming toll line L2 and an outgoing toll line L1 and a cord line for connecting them.

Fig. 2 shows the circuit arrangement of a final selector according to the invention controlled from the toll operators position.V

Fig. 3 shows a local connection made between two subscribers No. 23 and No. 34 over a so-called line selector and a final selector or connecto-r.

The final selector orconnector Ll/V. (Fig. 2) is in its constructional arrangement assumed to be a so-called panel switch board selector having lines divided into groups of 10 lines each. @23, Z223, 023 is one ofthese lines 'against which thewiper unit aIL'II, GII of the final selector or connector may be adjusted, e. the line of the subscriber` No. 23. The connector has a separate brush or wiper set or unit for each group of 10, i. e., 10 wiper units in all, which are all secured to a single brush-carrying rod, and which are all connected in parallel. These wiper units may be made Aoperative or inoperative selectively by a spreading and closingaction.

A single switching magnet H produces, by a stepwise lifting of the wiper rod, the selection of a group, the selection of one single line of the selected group and the release of the connector when the conversation is over. For obtainingthis result, the magnet receives three successive series of current impulses. To select for instance the lines (L23, Z223, 023, H is first energized twice and by this the wiper rod is lifted to such an extent that the wiper unit all, H, 0H will be moved just opposite the second group of lines. In this position a short energization of the brush set selecting or tripping magnet S will vcause the brush set all, 21H, all to be closed.' By threefurther selecting impulses through the magnet H, the brush-carrying rod is further lifted and the closed brushes of the set are brought into contact with the lines @23, 623, G23. At the end of a conversation the magnet H is switched over into an interrupter circuit, causing a further lifting of the brush-carrying rod up to its end position from which it is caused mechanically to fall to its initial position. During this further automatic lifting of the rod, thebrush set all, H, 0H, cooperates with a fixed spreading member which again restores the wipers to their initial spread or open position. The invention is not limited to this particular construction of the connectors. For a more specific disclosure of the constructional arrangement of connector switches of this character, reference is made to my co-pending application Serial No. 208,002, filed July23, 1927,`for selectors. p i

A limited number of relays is sufficient for controlling the connectorswitch L by reason of the simplification of the circuit arrangement according to the present invention. A `and B are two line relays connected to the line L1. Y is aline relay arranged at the outgoingline side of the connector, PI Vis the usual testing relay to determine whether the selected subscribers line is free or busy with a local connection. For testing the lines for busy for a toll-connection, a separate relay PH is used having one lightly and one heavily acting armature and two corresponding coils. rhis Jrelay l is the only additional member' rendering the circuit arrangement which is otherwise exactly the same as for a connector for local traffic) suitable for toll traffic. The further relays R, Q, and V are auxiliary relays, V being a slow release relay.

l The relays are designated by capital letters and the contacts belonging to them are shown on horizontally extended dotted lines passing through the axes of the corresponding relays. There vare `also provided (inthe usual manner) a so-called foot or head off-normal contact 7c of the connector, which varies its position as soon as the brush-carrier leaves its position of rest, and a cont-act w closed by the brush-carrier when leaving its position of rest, but opened again when the uppermost position is reached and remaining open during the downward movement of the rod. The contact ofthe magnet S is so arranged that whenclosed, it remains closed until the selector is released, even if the magnet S is deenergized. Y

The setting of the brushes of the final selector or connector, for example onto the line of the subscriber No. 23, is effect-ed from the toll operators position in such a manner that by ineansof a number of dial or another impulsetransmitter in the a-line with contact 11, two short circuit interruptions are given for the tens selection and thereafter three short interruptionsfor the units selection, whereas in the b-'branch a somewhat more extended interruption is effected at contact 12 following as a controlling impulse the tens impulses as well as the units impulses. During the selecting actions the 0,- and b-lines are also connected together by the contact e' behind the impulse contact 1l and 12 by which short circuiting the impulses are prevented from being heard at the other side of the operators cord circuit.

rWhen the line L1 is engaged by introducing after each impulse series, the 'relay Bis once deenergized for a somewhat longer time. B y

n closingitsleft hand back contact, the relay A transmits a corresponding number of impulses to the lifting magnet H in a circuit lpoleof battery, right hand middle front Contact of B, left'hand contact of R, left hand outer front contact of B, left hand back contact of A, coil H to pole of battery.

lVhen the magnet H is energized, the brushcarrier is raised first two and then three furthersteps. Y

Afterthe first two lifting steps, the brush set aII, bII, GII-is adjusted opposite the con- '2 tacts of the second line group and is ready for the tripping action or .closingin this position. The tripping' action is produced by the controlling impulse following the tens selection impulses, as on account of the deenergization ofthe relay circuit is closed temporarily for the brush trippingimagnet S, as follows:

tpole of battery, rightv hand outer front contact-of A, right hand outermost back contact of B, right hand outer front contact ofR, right hand outer Vback contact of V coil S, pole of battery.` l

The contact-of the relayS is closed and kept closeduntil the final selector is released. Therefore, when the relay Biis again energized, the slow release relay V is energized by a current in the following circuit -lpole of battery, right hand outer 'front Contact of A, right hand inner front contact of relay B, front contact of S,.coil Vto pole of battery.

Therelay-R has remained energized during the irst'deenergization ofB by'a circuit: n -l pole of battery, right handouter `front Contact of A,'.left hand back contactfof V, right hand'inner front contact of R, coilof R to pole of battery. Y

From the moment thatV has been ener- V gized therelay `R is controlled solely by the all further switching operations. areauto.

matic sequences offtlie ,saidnordinary second controlling impulse. The actionof the `two testing relays PI, PII switched on by this controlling impulse, whichy will be described hereinafter is independent of uany control o-f the toll operator and is only controlled by the momentaryfstate of the selected line @23, 623, 023-of the subscriber No. 23. Three'different conditions may arise: f i

(a) When subscribers .Zine s free stood it must be assumed that the local `connectionillustrated lin Fig. 3 by the adjustmentof a selector W1 does not exist.

The last controlling impulse effects, by means of the deenergized relay B, first an ordinary testing of the line' No. 23 to ascertain whetherit isv free or locally busy by means of the relay PI, 'and a moment later the toll test7 by means of therelay PII. Therelay PI isf-brought into circuit bythe relay B di rectly at its right hand outermost back contact, whereasV PII is brought into circuit by means of the slow release relay V deenergized by the relay B at its right-hand innermost front contact. rIn order thatiV will definitely release'its armature, `the controlling impulse has been chosen sufiiciently long asa-bove described. f

' `Thertesting circuit for the relay PI is as follows: 1 Y

-lpoleA of battery, right 'hand outer front contact of A, right hand outermostback contact of :B`,right hand outermost back contact of Rleft hand'and right hand coils of relay PI, right hand back Contact of relay Y, right hand middle back contact PII, testv brush GII, test line 023, coilof relay T23 to -p pole o-f battery.

PI and T23 are energized. WhileT23 disconnects the line relay R23pfro1n the called subscribers line,-PI makes the line busy forlocal connectionsby short circuiting its lefthand high resistance coil at its innermost front Contact Y v The slow release relayl V releasing its armatureafter the energization of PI connects at its right hand middle back contact the right Vhand coil of rrelay PII for thelight armature in parallel with the low resistance right hand coil of the test relay PI. The right hand coil of PII has been chosen in such manner that the light armature of PII, shown at the left hand side of the relay, is attracted and closes its front contact. This'prepares the bringing into circuit of the second left hand coil of PII for the heavy armature. This coil is brought into circuit if, after the said second controlling impulse, the vrelays B a-ndV are re-energized. The circuit for the left hand coil of relay PII is as follows:

,-lpole of battery, rightnhand outer front contact A, left hand contact of PII, third righthand front contact B, right hand inner In order that this condition will be under- Y at the toll exchange.

front contact of relay V, left hand coil of PII 4 pole of battery.

The heavy armature of PII switchesA over theY relay PI 'by meansof the middle right hand front contact of PII into the local circuit through the resistance coil as, while the outermost right hand contact of PIIdirectly connects the test line 02.3 through GII 5 0 the plus terminal, so that the subscribers line is now inade .busy both for local and toll calls.

PI remains energizedindependently of the switching operations of the relay PII and closes the circuit for the automatic ringing up of the subscriber andforA a free or idle signal to the toll operator. The ringing up circuit is as follows:

pole of battery, left -handvcoil' Q, second front contact from the left of relay PI, brush aII, wire a23 of the subscribers line,isub scriber station No. '23, wire 523 0f the subscribers line, brushlbII, resistance coil u, third front contact from the left of PI, right hand inner front contact of PII, alternating current source to -lpole of battery.

The relay Q is not energized by the ringing current as its right hand coil is short circuited by. means of the right hand back contact of relay Y` The ringing up current is periodically switched on and off in the usual manner by an automatic interrupter (not shown) arranged outside the final selector. During the interval between two ringing periods, the b-branch of thesubscribers line isdirectly connected with the plus terminal. A buzzer current for the free signal to the operator passes through the circuit -I- pole of battery, f. s. (free signal), lleft hand outer front contact of PI, right hand inner front contact of A, right hand coil of the relay B, left hand coil of the relayA to the other terminal of f. s; pole of battery, and isv transmitted Vby .means ofthe other coils of the relays Al and B'to the operator The free signal is interrupted and closed by the interrupter referred to above at the same time asthe ringing current. Y

If the subscriber No. 23 answers, the relay Q is energized by the direct current passing through its left hand coil and passing through both branches ofi-the line in series upon lifting the receiver at the station No. 23. Q when energized closes the'talking circuit through the connector LW at its left hand middle and inner front contacts and it also connects at these` contacts the relay Y to line 7223, The relay Y is energized and interrupts by opening its left hand back ccntactthe circuitof the relay A1 at the position of the toll operator, which, when fle-energized, opensits front contact the circuit of a supervisory lamp SL, so. thatthe operatorsees'from the extinguishing of the said lamp SL that the called subscriber answers. The relayY also opens at its right hand back contact the short circuiting path for the right hand coil of the relay Q, so that this coil helps in -maintaining'the relay energized. The'relay Q causes the relay-PI .Whew the subscriber@ Zinc s busy A with a local Comtecfiau- Under these circumstances the relay PI is not energized as in the selector VVLll of the localexchange connected tothe line,`the wire 028 is already connected to the plus terminal through the lowresistance upper coil of the relay P of the said selector WI in Fig. 3. The relay PIIA however, as before,is able to attract its light VarmatureV after theslow release relay V Vhas been deenergized.' The different behaviour of the two testing relays PI and PII produces the following action, differing from that described Linder (a).

The connection'betweenthe suby The ringing current circuit isnot `closed andinsteadof'a free signal, a busy signal is transmitted to the ytalking conductors of line LIby the following circuit g. Y i

-lpole of battery, from 5.8. (busy signall, right hand middle vba'clrcontact of R, left hand outer back contact of PI, right hand inner contact of A,right hand coil of B and left coil of AA (buzzer-coils) pole of battery. 1 1 l' 'n This busy signal is heard bythe operator as before. After theclosing ofthe left front Contact of PII the relay Q is immediately energized as followsz.' Y f z -lpole of'battery, right hand front contact of A, left hand front contact ofPII'right hand inner back contact' ofV, second back Contact PI from the left, left hand coil of Q to pole of battery.` Y

The aandZJ-branches of the line LIand of the subscribers line respectively upon energization of therelay Q are already con- I nected during the controlling impulsel referred to above. The subscribers both hear the busy signal, warningthem that they are going to be disconnected.

The breaking .down of the local connection is effected at theend ofv the controlling impulse when the leftjhand coilPII acting upon the heavy'armature becomes operative and directly connects, as before, the ywire 023 to the plus terminal.`"'By this, apart from Ille lio

terminate the ,busy7 signal, when the localy connection is brok-en down as upon re-energizing of the relay B at the end' of` the controlling impulse, the left hand inner back contactof B is opened producing deenergization ofthe relay A (and Al), already prepared bythe opening of the lefthand backr contact of the relay Y, so that they Contact of relay A in the busy signal circuit is also opened. Y

(c) When the Zine ofwsubsprz'ber 4No. .Q3 s busy 'with a toll connection In this case, neither'of the testing relays PI and PII is energized as the Wire 023 is already directly connected to earth by another connector such as LW adjust-ed to the line by the toll exchange. Therefore, the relay Qcannot be energized and the automatic operations hereinbefore referred to under (a) 'and (Z2) do not take place except the switching on of a busy signal. In the case (c), the toll operator is in a position to 4complete the `connect-ion by'repeating the controlling impulse without a repeated operation of the connector as soon as the called subscriber is no longer busy with the previous toll call.

As in either case the connection of the subscriber with the toll exchange is secured independentlygof the supervisory relay Y,

the subscriber can give flashing signals to the toll operator by vibrating or ogging his receiver hook without releasing the `final selector. n

The toll operator can again ring up a called subcriber who has answered but has prematurely hung up his receiver, simply by repeating the controlling impulse. The relay B deenergized by this impulse will open at its third right hand back contact thus interrupting th-e circuit ofrelayv Q, s0 that the circuit ,arrangement will again be brought into the same state as after the lirst testing operation.

The toll operatorl recognizes from the supervisory lamp SL and the free or busy signal given over the line LI, the condition of the calledV subscribers line.l If the lin-e is free, then the lamp SL is lighted after the controlling impulse has ceased untilv the called subscriber answers as the relay A1 is energized by the'following circuit:

.-lpole of battery, coil of AI, a-branch of theV line LI, left hand back contact of Y,

right hand coil of A to pole of battery.

` If the called line is busy, then the super- The connector can be influenced by the calling party by shortening of the controlling impulses in such mann-er that it acts in the sam-e way as an ordinaryv connector that it'can only be set upon free lines and .prevents the called subscriber connected up for a toll connection from being connected to other lines. The controllingcurrent impulse in this case inustfbe` so shortened that the slow release relay V is unable to release its armature and to switch on the testing relay PII. By thus makingvPII inoperative, all theV switching operations for toll trafiic y are prevented from taking place. This feature of the improved circuit arrangement can be applied in such manner that when the simple circuit arrangement of my present invention is used, an automatic exchange is provided with only one'type of final selector.

If the connector isruseol for atoll 'connection, it is then advisable to apply another periodicity for the ringingcurrent sothat it is `possible to -recognizebythe ringing that the toll exchange is calling. switching 4over from one periodicity yto another is 'effected by the toll test relay PII at its right hand inner contact.

' The release of the finalselector incase of a toll'connection is always effected by the operator.V vBywithdraw'ing the vcord jline plugfrom the jack of the line LI, the relays `A and B are deenergized, and therelay Q,

This

vswitch for local traiiic, or inotherV worlds, so

is also deenergizednf The lifting ymagnet 'l-l then receives current impulses and lbrings the connector swltch into v its position, of? rest bythe following circuit.: v

-lpole of" battery, a current interrupter (not shown), foot contact fw, leftV hand outer back contact of Q, left hand outer back con- Y tact of B, left lhand back contact of A, coil H to pole of battery.

In the-case oflocal connections, or if the switching on of the relay'PII has kbeen prevented by shorteningthe controllingimpulse, the connections are releasedin the same manner but in thiscase the called subscriber can free his line by deenergizing the relays Y and Qrby hanging up his receiver.

Having fully described my invention', what I claim as new and desire to secure by Letters Patent of the United States is l. In a telephone system having calling and called subscribers lines,ra tollkv operators position having incoming toll lines and yautomatic switches Vcontrolled by either a calling subscriber 'or 'the `toll operator for establishing a connection to acalled'line characterized by the fact that said switches are provided with means for automatically signalling the calling and called subscribers in case the line called by the toll operator is busy and for thereupon automatically breaking the connection to the other subscriber.

2. In a telephone systein having calling and called subscribers lines, a toll operators position having incoming toll lines and automatic switches controlled by eitherfa callingsubscriber or the toll operator for establishing a connection to. a called line characterized by the fact that said switches are provided with means automatically operative when the switches are controlled by the toll operator for distinguishing between busy called lines connected to local callingr lines or to lines through the toll operatorls position. 3. In a telephone system having calling and called subscribers lines,-a toll operators position having incoming toll lines and automatic switches controlled by either a calling subscriber or the'toll operator for establishing a connection to a called line characterized by the tact that said switches are provided with meansautomatically operative when the switches are controlled by the toll operator for breaking down a local connection and for signalling the toll operator without interrupting the connectionV when the called line is already engaged in a toll call.

4. In a telephone system having calling' and called subscribersv lines, aftoll operators position having incoming `toll lines .and automatic switches controlled byeither a calling subscriber or the toll operator for establishing a connection to a called line characterized by the fact that said switchesare provided with Vrestoring* means normally controlled over a subscribers line but con! trollable `automatically through switches adjustable by the toll operator whereby thecon-` nection to a called line .is `maintained if the called subscriber hangs up his receiver or depressesthereceiver hook in the case of along-distance call.

5. In a telephone system and called subscribers lines, atoll operators position having incoming toll lines and automatic switches controlled by either a calling subscriber or the toll operator for establishing a connection to a called line characterized by the fact that` `said switches are provided with restoring means controlled by the toll operator in the case of a long-distance call and that the tolloperators positionis provided'with means for automatically ringinga called subscriber who hangs up prematurely. f n

6. In a telephone system having calling and called subscribers lines, a toll operatcrs position having incoming toll lines and auhaving callingtomatic'switc'hes controlled/by either a'call?" ing subscriber or'tlie toll operator for 4establishing a connection to a called line characterized by the fact that said switches are provided with Va local test relay and a toll test relay, and that means is providedniii connection therewithwherebyonly the local testrelay is operative in the case of a local calling line and both test relays are operative in the case of a call initiated from` the toll-operators position, said switches being further provided with means whereby the. ,operation ot-the local test relay is ignored inthe case of a call initiated from the tolll operators position and a prior connection is interrupted except when the toll test relay indicates that the prior connection is a long-1 distance call.

7. In a telephone system having calling vided with means responsive to controlling' impulses of different character depending upon whether said switches are actuated by a local calling lsubscriber orgbythetoll operator,V said means being operative vtoautomatically complete a connection to a busy called line when the switches `are vactuated from the toll operatorsposition; Y 7

8. In a telephone exchange system, a connector switch havingmovable and'stationary contacts; toll lines arranged for .connection to said movablecontacts; local lines terminating in said stationary contacts and arranged iior connection toL said movable contacts; means operable through any one ofsaid lines for causing said` connector to'moveits movable contacts on the stationary contacts of a desired line; automatic testing means .associated with saidcoiinector for testing whether thevdesiredline is idle or busy; automatic guarding 4'means associated with said connector for making theline connected with busy; automatic ringing means for ringing upthe desired liiiewhen idle; automatic switching means operable in response to the setting of said connector over a local line for operating said testing, guarding and ringing means; and secondary testingmeans for determining whetherjthe desired line'when busy lis engaged in aA local or toll call, said secondary 4testing means being adapted to automatically connect said toll line with a called subscribers line even when busy byconnecting with another local subscribers line.

9. In a. telephone exchaiigesystem, a connector switch having movable and stationary contacts; toll lines arranged for connection to saidmovable contacts; local lines terminating in said stationary contacts and ai'- ranged for connection to said movable contacts; means operable by any one of said lines for causing said connector to move its movable contacts on to the stationary contacts of a desired line; automatic testing means associated with said connector for testing the condition of the desired line for busy or idle; automatic guarding means associated with said connector for making thel line connected with busy; automatic ringing means for ringing up the desired line when idle; automatic switching means operable in response to the setting of said connector over a local line for operating said testing; guarding and ringing means; secondary testing means for testing the local or toll busy condition of the desired line; said secondary testing means being adapted to connect the toll line with a called subscriber-s line even when busy by connecting with another' local line; secondary guarding means for making the desired line busy for toll calls to ot ier connector switches having access thereto; and automatic switching means operated in response to the setting of said connector over a toll line for automatically operating all said testing, guarding and ringing means and also said secondary testing and guarding means.

l0. ln a telephone exchange system, a connector switch having movable and stationary contacts; toll lines arranged for connection to said movable contacts; local lines terminating in said stationary contacts and arranged ;tor connection to said movable contacts; impulse-sending devices in connection with each of said lines for sending a series of numerical impulses and a controlling impulse after each of said series, the impulsesending devices of the toll lines being adapted to send a longer controlling impulse than those or" the local lines; means operated by the numerical impulses 4of said devices for causing said connector to move its movable contacts onto the stationary contacts of a de* sired line; automatic testing means operated by the controlling impulse following the last series of numerical impulses; automatic ringing means for ringing up the desired line when idle; automatic switching means operable in response to the setting of said connector when adj usted by impulses over a local line for operating said testing', guarding and ringing means; secondary testing means for determining whether the desired line is busy on a local or toll call, the last named means being adapted to connect the toll line with a. called subscribers line even when busy by connecting with another local line; secondary guarding means for making the desired line busy on toll call to other connector switches having access thereto; and automatic switching means operated by the extended controlling impulse of a toll impulse-sending device, following the last series of numerical impulses for automatically operating all said testing; guarding and ringing means and also said secondary testing and guarding means.

1l. In a telephone exchange system, a connector switch having movable and stationary contacts; toll lines arranged for connection to said movable contacts; local lines terminating in said stationary contacts and arranged for connection to said movable contacts; means operable through any one of said lines for causing said connector to move its movable contacts on the stationary contacts of a-desired line; a test relay associated with said connector for testing the condition of the desired line for busy or idle; a second test relay for determining whether the desired line when busy is engaged 011 a local or toll call; said second'test relay being energized in response to the set-ting of said connector over a toll line onto one of the said stationary contacts and being connected with a subscribers line in immediate connection with another subscribers line, the energization causing the connection oir' the desired line with the toll line and interrupting the local connection.

l2. In a telephone exchange system; a connector switch having movable and stationary contacts; toll lines arranged for connection to said movable contacts; local lines terminating in said stationary contacts and arranged for connection to said movable contacts; means operable by any one of said lines for causing said connector to move its 1novable contacts onto the stationary contacts of a desired line; a test relay associated with said connector for determining whether the desired line is idle or busy; a second test relay for determining whether the line if busy is engaged on a local or toll call, the same being operated automatically in response to the setting of said connector over a toll line; and a contact at said second test relay for connecting a battery potential to the third wire of the desired subscribers line and thereby short circuiting the first test relays of all other connectors adjusted onto said subscribers line.

13. In an automatic telephone system, a combined toll and local connector for use by an operator or by local subscribers in selecting and connecting with called lines; automatic testing means associated with said connector for determining whether the desired line is busy or idle; automatic testing means for determining whether the line when busy is engaged on a toll or local call and for breaking down a connection of the called subscriber with another local subscriber, the same being operated in response to the setting of the connector for a toll operator; and automatic signal means for announcing to the talking subscribers the impending disconnection of the local conversation in favor of a. toll call.

14. In a telephone exchange system, a conibined toll and local connector for use by an operator or by local subscribers in selecting and connecting with called lines; an impulsesending device associated With the tollL lines controlled by the operator and adapted to send ont numerical and controlling impulses; means 'for repeating said controlling impulses; automatic ringing means associated with said connector; and means operated by the repeated controlling impulses for bringing said automatic ringing means again into action.

l5. ln a telephone exchange system, a combined toll and local connector for use by an operator or by local subscribers in selecting and connecting with called lines; automatic ringing means for ringing up the desired line With a predetermined periodicity When idle, and automatic switching means operable in response to the setting of said connector over a toll line for sending the ringing current with another periodicity.

In testimony whereof I have alixed my signature.

FRIEDRICHV MERK.

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