US1772713A - Automatic telephone system - Google Patents

Description

g- 1930. H. M.'FRIENDLY 1,772,713

AUTOMATIC TELEPHONE SYSTEM Filed Sepf.10, 1927 5 sheets-sheet 1 5: v E Invaniurg HerhEfl-FPFriEndly I wlyg- 12, 7 H M. FRIENDLY 1,772,713

AUTOMATI C TELEPHONE SYSTEM Filed Sept. 10, 1927 5 Shets-Sheet 2 JumpErs Aug.12,1 930. H. M. FRIENDLY v v 1,772,713

' AUTOHATIC'TELEPHONE SYSTEM Filed Sept. 10, 1927 5 Street s-Sheet 5 549 Lisa I 1,502

. scribers line or other line.

Patented Aug. 12, 1930 T UNITED STATES PATENT OFFICE nmaar 1r. ramnnnr, or cmoaao, rumors Auromrrc mason stem Application mue umber 1d, 1m. lea-1110. stapes.

The present invention relates to telephone systems; more particularly so-called auto- 'matic ormachine switching telephone systems. I

General objects The general object of the resent invention is to enable a subscriber o the automatic telephone system, who contemplates leav ing the location of his telephone, to directlve- 1y set central oflice apparatus or call-forwarding enuipment associated with h s line througi the algency of his automatic calling device dia on his telephone, so that m caseany calls are thereafter directed to 1115 line the latter said calls will be further extended or forwarded to a predetermined sub- The latter said line may terminate at the switchboardof an operator whois char ed with respond ng to such calls and imparting such information to the party calling as instructed by the absent subscriber rimarily called. That 18, for ex ample, a p ysician, before leavin his oflice' may remove the receiver of his te ephone as if to initiate a call, and then 0 rate 1118 calling devicedial by placing his ore-fin er in a s ecific depression fingerhold of the ialand tiien draw the dial until his finger encounters. the finger-stop, so that when the dial is released it willsend a series of eleven open impulses. After the dial has returned, he will restore his receiver, leaving his central ofiice call-forwarding equipment in the set condition.

As will appear presently, that due to the said set condition, any call extended to the terminals of the said subscribers line will not only ring the bell of his telephone in the usual manner, but the call will be thereupon automatically extended or forwarded in accordance with the said set condition to an attendant who may possibly serve many such subscribers, or it may, as referred to, be ex tended to .a random subscribers telephone line as may be predetermined.

It -will also appear'presently, that if the subscriber has returned and, hears the bell he may respond in the usual manner and intercept the'call to the line to which in accordance with theset condition of his central oflice call forwarding ap aratus the call would be otherwise finally estined. This in terception also efiaces the said set condition so that his line becomes in normal condition and remains so after the termination of the call and until afain' directively set to forward calls as be ore. If the call is not intercepted b the subscriber as referred to, the centra ofic'e a paratus s cific to thefprimaril called su scribers ine will cause the cal to be forwarded tothe prearranged line. It will appear presently, that in case the call is forwarded to a switchboard operator who may attend to callsfor a number of subscribers accorded this class of service, the calls ex- .tended to her switchboard may be extended thereto over a group of trunks common to all calls.

It will thus be perceived that the generalobject of the present invention is to 'pro' vide for savin calls in the temporary absence of the called subscriber. This not only relieves the subscriber of the duty ofremaining near his telephone to receive ossible calls, but it saves the toll for the ot erwise futile call to'the operating concern. That is, ordinaril if no response is made to a call no-charge is collected for establishing the connection and the time the switching equipment is held. Under the arangement contemplated in the present invention, if no reassesses a charge for a completed call from the calling subscriber to the called subscribers line for which the calling subscriber pays as if it were an ordinary, normally responded call, as well as also assesses atoll against the subscriber primarilycalled covering the forwarding of the call. 'That is to say, the calling subscriber will pay for the call to the line rimarily called'and the subscriber of the line primarily called will I y for .forwarding it to the point to which it is forwarded. The operating concern thus in place of being unable to receive renumeration for a futile call, receives toll for two calls in yc'plllvedin the primary call and the forwarded Calls reguiring forwardin will usually occur at -business hours 0 the day when there is a sur lus ofv equipment, so that the forwarding 0 calls in which the double toll is collected logically comes at a time when there is ample equi ment and correlated plant in idleness tohan le it. Of course, such forwarding may occur during time of logically peak trafiic, but the 1percentage of such latter calls will be relative y low because telephones will usually have attendance at such times.

While a meter M for registering the number of calls completed and forwarded has been indicated in ig. 1, in order to simplify the disclosure, it will be understood that'any method of metering or prepayment collection may be employed under the contemplated use of the invention. For example, the operation of the meters may be determined in part by time of day the call is made, the destination of the call and the duration of the call. That is methods of operating the meter contemplated in any well known or other methods, as for example, the methods shown in my Patents 1,694,169 granted Dec. 4, 1928; 1,694,170, granted 4 1928; and 1,726,983, granted Sept. 3, 1929. it also contemplates the' llection of pre-payment deposit as well known, and also setforth in the latter said pliant. a

Drawings With reference to the accompanying drawin i-'.

' Fig. 1' shows a-subscribers tele hone A and companion line switch B; thesai line switch having common access to the switch group containin the secondary line switch Fig. 2 s ows apparatus, nearly all of which isspecifically employed in forwarding calls whli ch age primarily destined to telephone A.

1g. s from the switch group containing secondary line switch C, together with other indicated automatic switches and called telephones of well known systems. I Fi 4shows a well known so-called upselectlng connector E, a group of suc connectors having access to a group of lines I including the line extending to'telephone A in Fig. 1.

Fig. 5 shows the impulse .train transmitting apparatus cooperative with the apparatus shown in Fig. 2.

- Fig. 6 shows a preferred modification of Fi 2. a

Fig. 7 shows a plan view of the dial of the lustrated in Figs. 6, and 11 rotary ows a first selector F accessible present invention used on the callingdevice (.40) on telephone A.

Fig. 8 shows a cross section along the line '8-8 in Fig. 7 disclosing the detail of the Fig." 11 shows apreferred modification of 9 shows a modification of Fig. 2. 10 shows a preferred modification of Fig .h2. g e accompanying five sheets containing the dra illustrating the exemplary embodiment o the present invention chosen to disclose it are assembled so that correspondingly designated lines extending toward margins register so-termed preferred modifications ilare to be considered as forming a part of 2. These modifications were not actually included in Fig. 2 in order that the drawin would be less involved and the disclosure t ereof more simple. That is, it has been deemed expedi- The ent to first disclose the main operation lndependent of certain detailed, preferred operations in its comprehensive embodiment.

- The telephone A is' of the well known common battery automatic t but equ p ed with an automatic calling evice and dla of the present invention shown in Figs. 7 and i 8 so that a series of elevenimplulscs can be sent therefrom b 0 rating t e dial from a novel finger-ho d o the The primary line switc B and the secondary line switchv C are of the well known class as: described in the third edit on of Hershe s Automatic Telephone Practice,

age 53. owever, thelower wiper, as well as the lower armature of the left-hand relay shown on these switches, are specific to the present invention.

The first selector F is of the well known class-as des'cribedin the said book on pages .59 to 61. However, the lower set-of ofi-normal springs, the upper armature of the release relay, the upper armature of the switching relay and associated circuits are specific to the present invention.

The switch elements NO and DF have the same general mechanical structure 'and operation as the line switch B, though the operating circuits are specific to the present invention. r

The dial of the calling device shown in Figs. 7 and 8 (and the calling device not shown) belong to the well known class as described in the said book of Hersheys on pages 15 to 17. However, the finger-hold or depression used in setting the calling device to send eleven open impulses is specific tothe present invention.

resent invention.

The line switches LS and LS are like line switch B.v a I The selectors G, H, J, K, L,-N, P and Q are well known selectors as disclosed on pa cs 59 to 61 in the said book of Hersheys.

e connector R is like connector E.

The tale hones AA, A and A are llke tele hone I 4 T e connector E is of the well known socalled group-selecting type I asdesignated Fig. 111 in Hershe -s fourth'edition of his book Automatic Te ephgne Practice.

The selectors G, H, J indicated in Fig. 3 may described inthe third edition of said book of Hersheys, on pa cs 59 to 61.

The connector indicated in Fig. 3 is ofthe exact type of connector E in Fig. 4, or it may be any other suitable connector, as for example, the connector described in the third Initiating a call from telephone A to tele- I phone A Upon removing the receiver from the switch-hook of telephone A a circuit path can be traced from ground, armature .12, conductor 13, make-before-break spring 201, armature 202, conductor 203, telephone A, conductor 14, armature 205, make-before-break spring 206, conductor 207, resistor 16, armature 17, winding of slow-releasing relay 19 to grounded battery, the latter said relay opcrating. In view of the stated well known operation of the switch B, its detailed operation in selecting and seizing the first accessible idle secondary line switch C will be understood. For thesame reason, the detailed operation of the switch C in selecting the first accessible idle first'selector F will be understood. The first available idle selector F is thus seized responsive to the subscriber removing the receiver from the switch-hook of telephone A.

A large group of line switches containing switch B have common access'to a smaller grou of secondary line switches containing switc O. The group of secondary line switches containing switch C then has common access to a smaller group. of first selectors containing switch F. The group of first selectors containing selector F has common access to a group of second selectors contam- I containin K L N P and Q be (if the cxact class .mature 23 is a .plie

ing selector G. The up of second selectors I i I selector has'common access to 1 Ya group 0 third selectors containing selector H and the up of third selectors containing se ector H as common access to a mu of connectors containing connector lhe cup of connectors containin connector R as common access to the telep one line leading to telephone A a When the telephone A has beenextended-to the first selector F, as setforth, switching relay 20 of switch B is actuated. Also, switching relay line relay 301 and slow-releasing release relay 302 of switch F are actuated.

When relay 19 actuated forthwith responsive to the removal of the receiver from the switch-hook of tele hone A, ground on ar- I d over release trunk conductor 24, con uctor 25, armature 208 to the winding of relay 209, the latter relay actuating to apply ground through its armature 210, conductor 211 to private bank contact 412 and its multiples to guard the line leading to telephone A against intrusion by a connector of the group'containing connector E.

Tom to indicate when call has been was to first selector When relay 302 in selector F actuated, a circuit was thereby closed'from grounded ofinormal spring 304, armature 305, conductor 306, bank terminal 26, wiper 27, armature 28,

I bank terminal 29, wiper 30, armature 31, conductor 32, make-before-break spring 213 to the winding of relay 214, the latter said relay actuating and locklng through its armature 215 to ground on conductor 25. At the time relay214 was energized ground on conductor 32 also energized relay 216, the relays 214 and 216 thus actuating slmultaneously. Specific tone from source ST is thereupon applied through armature 217 upper armature of relay 216 to talking conductor 14, audible to the party at telephone A, indicative that the connection has con extended to first selector F and that the first selector F is in readiness to respond to the dial of telephone A.

It will be noted, in this connection, that the conductor 25 now receives ground back from attracted armature 308,. release trunk 309, bank terminal 33, wiper 34, armature 35, release trunk 36, bank terminal 37, wiper 38, armature 39 to the conductor 25, audit will appear presently that conductor 25 will be maintained grounded from ahead so long as the receiver of telephone A is kept off the switch-hook so that relay 214 will remain locked until the call is abandoned by the calling subscriber at telephone A.

.Callz'ng subscriber semis first digit of called I line number I Upon the calling subscriber operating his calling dial 40 in accordance with the first 21 of switch C is actuated. Also, Y

Ill

digit ll of the telephone number 83241 of the line extending to telephone A, the relay 801 will momentarily retract its armature 812 three times responsive thereto, causing the wipers 313 to 315 to be aligned with the level of bank terminals and there rotate-in and select the first idle trunk leading to second selector G, the operation of selector F being understood in view of .the reference to the third edition of Hersheys book, need not be detailed. However, it ma be stated that after the second selector has been seized switching relay 316 is the only relay in the selector operated, relays 301 and 302 deactuating in sequence responsive to the actuation of the relay 316 in effecting the seizure. The release trunk 309 will receive ground back from selector G, in the well known manner before armature 308 retracts so there is no lapse of ground potential on conductor 25.

Calling subscriber sends but four digits It is thought, inview of the reference to the third and fourth editions of Hersheys book, the successive operation of the selectors G and H responsive to the second and third digits and the operation of the connector R responsive to the last two (fourth and fifth) digits to complete the connection from the' 10 tele hone A to the called telephone A will be y understood. Y

At the time the wipers 313 and 315 were stepped ofi-normal and spring 304 disconnected from its cooperative spring the ground traced to relay 216 is thereby disconnected, so that relay 216 deactuates responsive to the first impulse sent from the dial 40 and disconnects the tone source ST. However, due to the locked condition of relay 214 ground applied through armatures 218 and 219 1s conducted to the winding of relay 220, causing the latter said relay to-lock by its armsture221 to conductor 25, thus positively disabling the application of tone from source ST so long as the present call is maintained.

Response at telephone .4

When the subscriber at telephone A' removes his receiver from the switch-hook in responding to the ringing of his bell, current traversing the heavy talking conductors, an including the telephone A, will be thereby reversed in direction. This will cause the differentially energized magnet 'of the meter M to operatively energize cumulatively to register a call against the telephone A.

It will be noted that the (lower) polal'lziwlifi winding of the magnet of the meter M be energized whenthe conductor 24 becomes current then traversing the shunted (upper) operating winding ter said meter is then in opposition to the polarizing winding. However, when 1 the called subscriber at telephone A is thefirst one of grounded when the call is first initiated. The wipers 42B of the magnet of the latg a busy tone to be apphed audible m the reremoves his receiver from the switch-hook and causes the direction of current traversing the shuntingresistor 16 and the ofierating winding of the magnet of the meter to be changed in direction the two windings of the magnetof the latter said meter energize cumulatively and cause the meter to register and the armature 41 to short-circuit the resistor 16 and the operating winding. In view of the adjustment of the magnet of the meter M, after the armatures thereof operatively attract they will be maintained in their-attracted position by the polarizing winding, regardless of the fact that the armature 41 has short-circuited the resistor 16 and the operating winding to improve the talking transmission. Abandoning the call phone A When the subscriber at telephone A replaces his receiver on the switch-hook the connector R will be restored andthis will incidentally remove the ground from the release trunk forward extension of conductor 25, so that all relays maintained locked from this ground dcactuate. The circuits are now at normal and idle. It will be noted in this connection, that had the calling subscriber at telephone A hung u his receiver first, while the called subscri r at telephone A maintained'his receiver 05 the switch-hook the connector B would not restore until the latter'said subscriber hangs up his receiver, although the ground will be momentarily removed from the release trunk back from the connector R to unlock all relays dependent upon ground being maintained on the re-' lease trunk including conductor 25.

Y Call from telephone A to telephone A under 7 normal conditions In view of the reference to the third an by subscriber at telefourth editions of Hersheys bo0k,. it is 4 thought that the extension 0 telephone A, through line switch LS, first selector J, second selector N, third selector Q and wipers 423 to 426 of connector E to the bank terminals 427, 412, 428 and 429, respectively, (being telephone number 22312) will be fully understood.

d Only first lineglfaqroup of three arranged for .fomarding n ccamplcd embodiment a call from the However, in this connection, it will be' ex plained that the line leading to telephone A agroup of three lines belonging to the same subscriber all of which may be called by calling the same telephone number 22312. If the first line is busy the to 426 of the connector E will pass on and seize the first idle line of the up'tested, and if none are idle will cause ceiver of the callin' telephone.

In view of the re erence to the fourth edithe private bank terminal of the first line of the grou cooperative with private wiper 424.

will-be tiedto its companion up private bank terminal cooperative wit line of the group, ere bein no such tie for the last line of the, group. he said tie enables the connector to automatically step its wipers on to the'next bank terminals horrespon'din to thenext positioned line of the group i the tested'line is busy. The absence of. this said tie disables the connector for automatically step ing its wipers on if the tested line is busy. he absence of the said tie also enables the connector to a ply a busy tone audible in the calling telep one in the event a connector'as will only app he busy tone if all the lines of the grou it is operated into selective relation wit are busy. Of course, one line ma constitute the roup and in that event if the line is busy "t e wipers will not be stepped on and the busy tone will be thereupon applied, since the bank terminals cooperative with wipers as 423 and 424' are not to under the condition. Y

There is usually a group of connectors as E having common access to groups of lines be tied together and perhaps single lines as well. The usual practice is to multiple the respective bank terminals correspon ng to 427 to a conductor as 431, and the terminals corresponding to 412 to a conductor as 432. These conductors from pairs ofcompanion bank terminals are connected to thecorresponding bank terminals of each'common connector and the airs of conductors correspondin to 431 an 432 are left unconnected only i the corresponding-linepis the last line of a group or 1s a single dine. That is, respective pairs of conductors as 431 and 432 corresponding to companion" terminals simultaneously engaged by wipers as 423 and 424 are tied together for 1 all lines .of a group excepting the last line thereof. This admits of assembling1 grou s and individual lines at random in t e ban g It will be noted that bank terminals 427 and 412, and respective multiples, correspondin to the first trunk of the group d esignated y the calling number 22312 are tied together over conductors 431 and 432 through "spring 230 and that the corresponding bank 424) for the next succeeding line 0 thegrou are permanently tied to ether by he 433,.

terminals (cooperative with wi rs 423 while the corresponding ank terminals for the next (third as well as last) succeeding line of the oup are not tied. The arrangement is thus ecause only the first line of the group ofthree lines is arranged for forwarding. The last two lines of the oup lead directly from pairs of line terminals 434-435 and 436-437, to telephones A! and AA, respecwiper 423; this being the arrangement for all-but the last sitions 22313 an 22314) wi (5 will appear presently. That is to say,

P to the first or second line 0 tively, but are only indicated .to avoid involvmg the disclosure unduly.

When first line of group is at z'ng the following lines of t a group are barred when group number is called So it will be understood that normally the first idle line of the group of three belongi to the subscriber having telephone A wi fi be seized and rung upon responsive to setting the wipers 423 to 426 upon t a bank terminals corresponding to telehone number 22312; However, thelast two ines ofthe grou (occupying numerical o- 1 be disable so far as bein connected to b calling the telephone num r,22312 at suc time as the subscriber may set his first line of. the group leading to telephone A so that calls to telephone number 22312 will be forwarded as or forroardonl under t said set condition all calls whereiii the wlpers 423 to 426 (or corresponding wipers of any eonnectorof the group containing connector E) are set upon bank terminals corresponding to the firstline of the roup 22312 will then be forwarded to a pre etermmed line (in the present instance telephone A) outside of the group, and if this first line of the group is busy to give the busy tone to the calllng part One call can be forwarded and maintaine so at a time, in the arran ement shown in the drawings illustrating t a present system, though, it will be fully disclosed .presentl how this may, if desired be applied to all t e lines-of the group. It has been illustrated in the limited manner to alvoid unduly involving the complete disc osure.

When first line of group is not set for for It. will be noted that thefirst line of the said group is numbered 22312, while the following two of the group are positioned as numbers 22313 and 22314, respectively. The second and third lines may be reached by directively calling the corresponding said telephone numbers or by directively calling the number of the first line of the group only under normal non-set condition, wherein the connector will automatically advance to the second or third line of the {group responsive the group being busy, as is well known, in view of-the reference to the fourth edition of Hersheys book.

ing the group of lines denoted by telep one number 22312, the operation of the system responsive to settin the wipers 423 to 426 upon the first line 0 the group will be procceded with, having in mind the line leading to telephone A is not set for forwarding calls.

contemplated by the present invention, as

With the foregoing explanations re ard- Line leading totelephone A busy If it is assumed for the moment that the I line extending to telephone A is busy by hav- (and its companion tied terminal 427 ing been seized by another connector of the roup containing connector E or a' call has en initiated from tele hone A, the private bank terminal 412 and t 1e companion group private terminal 427 tied through spring 230 will constitute round potential. .The initiation of a call roin telephone A causes the ground to be applied to ank terminal 412 y armature 210 in a manner peculiar to t e present invention as has been described. The well known operation of the connector E will cause the private terminal 412 and companion terminal 423 to constitute ground potential if the line to telephone A 1s connected with by a connector of' the group containing con nector E.

Under the condition, the wi ers of a connector set u on the line termina s corresponding to the ine leading to telephone A will step on to the next successive set of bankterminals corresponding to the .second line (leading to telephone A) of the group, in the well known manner for connectors of the stated type.

Line leading to telephone A idle When the connector E seizes the line extending to telephone A (now assumed to be idle) itswiper-closing relay 437 will cause ground otential to be applied through wiper 424, ban terminal 412 (and multip es) conductor 432, conductor 211, armature'210 to the winding of relay 236, the latter said relay actuating, its armature 237 applying ound through spring 238 to conductor 25, e ective to disconnecting the rela 19 and the ground normally applied throng armature 12, in the well known manner and in view of the reference to the third edition of Hersheys book.

The ringing current from source G is ap-' termittently a plied to t e bell 42 until the callin subscri r at telephone A. abandons the ca 1, or the subscriber at tele hone A removes his receiver. from the switch-hook in position,

open impulses. It will be noted that'the deresponding. If the latter the telephone A is ener through the back-bri ge 442 of t e connector E, after the ring-cut-o relay 438 operates.

It will be u ted that the 240and 241 short-circuit the rightand and left hand windings of unlatchmg magnet 242, the

ob 'ect of which ma at will appear presently.

e calling telep one A an t ephone A are now in talking relation, the actuation of relay 442 havingreversed the direction of current traversing the telephone A. The talkin path from the wipers 425 and 426 to telep one A is the same as that traced for the rin 'ng current to hell 42. The connector E wi restore responsive to the last said party to the connection hanging his receiver on the switch-hook.

the line leading to telephone A so Setting calla directed'thereto will be forwarded to I telephone A, the number of which is Let'it be assumed that the subscriber of telephone A desires to have all calls directed to his line oup No. 22312 forwarded to telephone num r 33241, which is tributary to a different central oflice fromthat' to which the line to telephone A is tributary though the call may in like manner be sent to a line tributary to any oflice of the s stem.

Remembering that the 'al 40 on telephone A is like that shown in Figs. 7 and 8, the subscriber at telephone A will remove the receiver from the switch-hook to' initiate the call, causing the tele hone A to be extended to first selector F and the relays 209, 214 and 216 to actuate for the objects before mentioned.

The subscriber will now appl his fin r to the depression Z of the dial as shown in i 7 and 8 and draw the dial around until finger encounters the finger-stop and thereupon release the dial to restore to its normal the while sending a series of eleven gflession Z takes the place of a hole for a gar-hold correspondin .to the digits from he called 1 to 0.. This depression old is employed so as to not confuse the subscriber when sending by employing thenumeral holes in the 1a The selector F will operate in the manner before referred to; but this time aligning its wipers with the eleventh level of bank terminals, in place of the third level. The relay 216 in Fig. 2 will deactuate res onsive to the first ofi-normal movement of t e wi ers 313 to 315 of selector F, and relay 2 in Fig. 2 will thereupon actuate and lock to conductor 25 in the manner as before described. However, upon the wipers 313 to 315 with the eleventh levelof bank terminals, t e shaft 320 will cooperate with the springs 321 and closethem, the wipers 1st ing bank terminals 323 to 325. The windings of slow-releasing relay 327 will now be 1 At the time the shaft 320 closes the springs in series with the tele hone A and attracted armature 328'will app y ground through bank terminal 323, wi r313, armature 330 to release trunk con uctor 309 before armature 308 has had time to retract, so that ground is maintained on conductor 24 and exten sions, for the urposes above mentioned.

321, and before the wipers have had time to rotate in and seize the terminals 323 to 325 wherein relay 316 will actuate, a circuit can be traced from grounded armature 308, conductor 309,.armature 331, springs 321, conductor 306, and over the traced path to conductor 32, to re-energize relay 216, causing the later said relay to actuate-to close a path from ground, armatures 218, 219, 241, spring 242, make-before-break spring 243, to the winding of slightly slow-releasin relay 244, the latter said relay actuating an looking to grounded conductor 25. Ground on armature 245 is applied to energize relay 246 causing it to o erate its s ring contacts and tripping the 0g 248 be 'nd the armature proectron 249 on the relay-246. I Tone indicates when set becomes efiectioe When the rela% 246 actuates, distinctive tone from source will be applied through spring 251, armature 252 to ta king conductor 14, audible to the subscriber at telephone A, indicative to him that the relay 246 has actuated to set the first line of his roup for forwarding all calls directed to t e group when the first line is idle and for barring successive lines of his group against seizure by group-selection operation of the connector concerned. Of course,-directively calling the second line of the grou will cause theselected lineto be seized 1f idle and the connector to rotate ofi' to the third line of the group in the normal manner as if the stated setting for forwarding calls had not been made. i

Means for b arring mceeaaive lines of group The barring of the successive lines oft he group under the condition mentioned in the foregoing paragraph-is accomplished through the agency of the spring 230 disengaging itscompanion contact and thereby openmg'the tie between conductors 431 and 432 so that busy gnoundpotential, cannot be applied to bank terminal 427 andvits multiples.

It will be noted, in this connection, that at the time the relay 246 actuated the shortcircuits were thereby removed from the windings of the magnet 242. This included them in series with the telephone A, so that the as dog 248 was thereby raised out of engageknowingl applied to private banlg ment'with the ative result. u I

The subscriber at telephone A upon'hearing the tone from'source T. and therefore replace is receiver on the switch-hook. The wmdings of magnet 242 will forthwith deenergize, allowing the dog 248 to retract and dro over the projection 249. Theground wili bemaintained on the release trunk conductor 24 consistent with the slow-releasing characteristic of the release relay 329, so that an interval of time will occur after the do 248 retracts before the relay 244 will unloc andthereby deenergize the relay 246. When the latter occurs, its armature projection 249' is mechanically locked by the dog 248, so that the springs of relay 246 are held 1n their actuated positions, although the winding'ofthe relay 246 is unenergized. The lineleading to telephone A is now set so that any projection 249, but to .no oper that his line has been duly set, will calls directed to it will be forwarded to telephone A, the numerical position or telephone number of which is 33241. Subscriber at telephone A may make-outgoing incoming calls I Let it be assumed that the subscriber at telephone A desires to make an outgoing call during the time the line is set for forwarding calls made to it. It-will be noted that the relation between the line conductors lea'din between the telephone A and the winding of relay 19 and ground on the resting contact of armature 12 of the -rimary line switch B has not been disturbe by the set condition of relay 246, so that outgoing calls from telecalls while the line is set to forward phone A will be normal under all conditions when the line is idle.

Call to line leading to telephone A while relay 246' is looked, and thelzne is therefore set 'to forward calls to telephone A the actuated state of relay 209 under the condition.

When the line leading to the telephone A (assumed idle) is seized by the connector E, busy ground is applied, by the connector E to private bank terminal 412, and this ground is then applied over conductors432 and 211,

armature 210 to operatively energize relay 236. Ground is thus applied through armature 237, spring 238, armature 252 to the winding of relay 253, the latter said relay actuating. This opens the talking path beterminal 412 due to I tween the telephone A and the primary line copper tube) that it w v connector from the winding of slow-releasing line relay switch B. However, it will be noted that the ringing path to the bell 42 is the same as before described, with the sole exception that the windings of the magnet 242 are in series therewith. The core of the latter said magnet is so designed (as b shielding it by a ill not be operatively susceptible to the alternating ringing current, from source G, when in series with a condenser at the bell 42, but will operate it an energized conductive path is closed through a source of direct current, as b the removal of the receiver from the switchoo k of telephone A. The bell 42 will thus start ringing res onsive to the said seizure by the scriber of tele hone A hears the bell he may respond and t ereby un-set his line'and proceed as if his line had not been set, when the call was extended to his line. This operation will be taken up in detail later on.

Forwarding operations Returning to the. actuation of relay 253 responsive to the connector E seizing the line leading to tele hone' A, a circuit can be traced 19 in the primary line switch B, armature 17, conductor 207, make-before-break spring 206, armature 255, conductor 256, armatures 501 and 502 in multiple, conductor 503, armature 257, make-before-break spring 201, conductor 13,- armature 12 to ground, the relay 19 actuatin It will be noted that the loop including t e armatures 17 and 12 of the primary line switch B is equivalent to the condition when a call was describedinitiated from telephoneA, so that it 'will be clear that the primary line switch B will 0 erate to extend the connection from multiplied armatures 501 and 502 to a secondary line switch as C, andthat the latter will then further sponding to the number of telephone A.

extend the connection to a first selector as F.

When 'the first selector F is seized and ground from spring 304 is applied back over the before traced path tothe windings of relays 214 and 216, the latter two relays actuating the relay 214 looking to release trunk ground, as before described. Ground will now be applied from armature 258, through armatures 259 and 260, conductor 261 to the winding of relay 504, the latter 'said relay actuating to start the predetermined directive impulse series -train corre- Inasmuch as in the assumed case the call is to be forwarded to telephone number 33241 (telephone A), the terminals on the crossconnecting rack set X corresponding to the numerical orders of the five digits of the telephone number of the telephone line leading to telephone A will be jumpered to digit terminals Y on the cross-connecting rackhaving the designated digit value corresothat in the event the sub-- mums spending with the-numerical order rank of t e di ber, t e cross-connecting rack terminals Y being designated in accordance with their digit value to correspond to the bank sitions of corresponding, digit value 0 the switch DF.

It will be clear, presently, that if it were 539- 536, u" per armature of relay 504 to the winding 0 relay 515, the latter said relay actuating and locking to the attracted armatelephone A is therefore un-busied and therefore subject to seizure while the shafts 552 and 533 of switches NO and DF', r tively, are oif-normal the relay 515 wil be prevented from being energized responsive to a new seizure of t e line leading to telephone A until the wipers 513 536 and539 are in their drawn ositions. the line correspon ing to telephone A may beseized, causing the relay 504 to rea-ctuate, before the switches NO and DF have had time to restore, but the relay 515 cannot initiate the sending of impulses until the latter said switches have first restored to nor mal. This operation will be described in more detail presentl The interrupter F mately twelve revolutions per secon being the rate it is desired to send directive imulses to the switches forwarding the call. e first impulse delivered over conductor 516 through armature 517 after'the actua- .terrupter I until relay 523 actuates, as will a pear presently. However, it will be noted t the traced path including conductors revolves at a proxits of the letter said telephone num- 'ture 514. This closes theconductor 516 lead- 'lhat is to say, 1

Ill

III

256 and 503 will not be opened by the attraction of the armature 501 so lon as armature 502 remains retracted. hen wiper 524 is stepped to bank terminal 527 responsive to the interrupter 1 ground isapplied from ground 528 over conductor 529 throu h armature 530 to the winding of relay 531, the latter said relay actuating.

Sending of forwarding impulses wiper 536 engages bank terminal 535 a circuit path can be traced from grounded armature 511, wiper 513, jumper 538, digit terminal3 of the cross-connecting rack group Y, bank terminal 535 wiper 536, wiper 539, bank terminal 540, conductor 541 to the winding of slow-releasing relay 523, the latter said relay actuating, armature 530 locking it through wiper 524 to ground 528 so long as wiper 524 is off the bank terminal it is shown resting upon. When the relay 523 actuates, armatures 501 and 502 will retract to maintain the closure of the circuit path including the conductors 256 and 503 in order to give the selector F time to. rotate in and seize the first idle trunk extending in the direction of the telephone A; leading to second selector G, Armature 545 applies ground received from conductor 529 overconductor 546 and through the interrupter contact and armature 547 to operate the motor magnet 520 to restore the wipers on shaft 533 to the drawn position at which position the ground 528 is free of conductor 529.

Armature 549 applies ground to the winding of motor magnet 550, so when relay 523 deactuates the Wipers on shaft 552 will be advanced one step.v Wiper 513 now applies ground over jumper 553 to bank terminal 535, corresponding to digit Also, due to the deactuation of relay 523, the interrupter I will start driving the wipers on shaft 533 in the manneras before described until. the wiper 536 encounters bank terminal 535, causing three open-impulses to be transmitted from armature 501 effective to selector G, the Wipers on shaft 533 restoring to the drawn position thereafter as before described when the first series of three open in'ipulses were sent. The shaft 552 will be caused to advance its. wipers when the relay 523 deactuates following the sending of the second digit 3. Wiper 513, now applies ground over jumper 556 to bankterminal 557 correspond,- ing to digit 2. i

lhe wipers on shaft 533 will now be driven until wiper 536 encounters bank terminal 557, at which time the relay 523 will actuate and lock and the wipers on shaft will be restored to the drawn position in the manner as before described, the armature 501 having sent a series of two open impulses effective to third selector H. In view of the jumpers 561 and 562 two more series of open impulses will be sent; the one corresponding to j umper 561 being a series of four, and the one corresponding tojumper 562 being a single impulse. The last two series serve to set the connector R on the terminals of the line (assumed. idle) leading to telephone A, the connector R thereupon applying ringing curre nt to operate the signal bell'of telephone Bell of telephone A is rung while call is being forwarded and until subscriber at telephone A responds During the sendin of the train of series of open impulses to efiect the forwarding extension to the line leading to telephone A the bell 42, of telephone A has been periodically ringing responsive to sourceG, applied from the connector E, so that the subscriber thereof (telephone A) if at hand may respond and thereby efface the extension of the call towards or to the telephone A and thereby destroy the set-up condition by operating the magnet 242, as will appear presently.

Let it be assumed that the subscriber of telephone A does not respond to the call during the time the forwarding extension train of series was being sent or before the response at telephone A. ,7

At thetime the motor magnet 55 0 retracts the fifth time following the termination of the fifth digit series and before the shaft 533 has had time to stepits wipers in two steps, ground is applied from bank terminal 563 where ground potential has existed since te relay 515 first actuated ,and so constantly maintained), wiper 564, conductor 565, makebefore-break spring 263 to the winding of relay 264, the latter said relay actuating-and locking through armature 252, spring 238, armature 237 to ground, it being remembered that the ground is maintained on the armature 237 of relay 236 by the connector E energizing the latter said relay.

Subscriber (22 telephone A can answer calling party untilealling party hangs up Responsive to the actuation of relay 264, a

at any time until the call is abandoned by the calling subscriber and thereby come in on the connection and efl'ace tho forwarded extension and become in direct talking communication with the calling party, as if the line extending to telephone A had not been set to forwarded'calls directed thereto.

\Vhen the relay 264 actuated and relay 253 deactuated, the windings of the polarized relay 265 is placed in bridge of conductors 13 and 207 extended to connector R. While the bell of telephone A is being rung, the armature of the polarized relay 265 is tilted counter-clock-wise so that the slow-releasing relay 266 will be operatively energized.

Response at telephone A comes current to be reversed through calling telephone A \Vhen the receiver is removed from the switch-hook of telephone A the currentprojected back from the front-bridge rela of connector R responsive to the actuation oi the back-bridge relay of connector R :will hereversed in direction through the winding ofv the polarized relay 265, under which condition its armature will tilt clock-wise so that relay 267 will be operatively energized, the relay 266 deactuating consistent with its slow-releasing characteristic.

The armature 270 will now close a conductive path including the retardation coil 271 in series for operating the ring-cut-ofi relay 438 in connector E, followed by the actuation of the back-bridge relay 442. So the current will not only be reversed back to the polarized relay 265 responsive to the subscriber at telephone A removingthe receiver from the switch-hook, but the current will be reversed back over the line including calling telephone A by the operation of relay 442, consequent thereto.

Tone to indicated call is a forwarded one It will be noted that after relay 267 actuates, and before relay 266 has had time to deactuate, the distinctive tone from source AT is a plied through armatures 272, 273 audible to t e party at telephone A and the party at telephone indicative to them that the call was a forwarded one.

Recording number of calls forwarded least there will be a record made on the meter of a completed call.

Meter of line primarily called registers forwarde calls It will be noted that the reversal of the current back from'the connector B when the party at telephone A responds will affect the meter M associated with the primary line switch B as when a call was described as initiated at telephone A and responded to at telephone A, so a call is registered against the subscriber of telephone A covering the forwarding of the call. The meters M and M thus enable detailed information to be had as to the number of calls assessed to the subscriber of telephone A and the number of these which represent forwarded calls.

Indication by tone given calling party while zcall is being forwarded from the called "from spring of relay 246 to the right han terminal of the winding of retardation coil 271 to effectuate the stated object.

Talking path between calling telephone A and called telephone A When the relay 267 actuated, the talking path from telephone A to conductors f 439-440 is continued through condensers 281-282, armatures 205-202, springs 206-201, conductors 207-13, armatures 17-12 respectively," and over the heavy talking conductors to the telephone A.. From conductors 430-440 a line pair leads through windings of magnet"'242, line conductors 14-203, respectively, to telephone A, the impedance of the windings of magnet 242 being sufiicient to prevent undue attenuation of the currents constituting sound which pass between the telephone A and A because of the electro-static capacity of the line conductors leading to telephone A.

Subsci'ibei at telephone A replaces receiver on-switch-hoolc while subscriber at telephone A retains his receiver of 1 from the bridge, so that the back-bridge relay 442 in connector E will deactu ate. The winding of polarized relay 265 is still in series with the front-bridge relay in connector R, so that the latter said connector is still in seizure of the line leading to telephone A.

Subscriber at telephone A 'replaces receiver on switch-hook Upon'the subscriber at telephone A now replacing his receiver on the switch-hook the front-budge relay 446 in connector E will deactuate and cause the obvious circuit for the release ma net of connector E to energize to restore said connector E. This will remove the ground from conductor 211, so that armature 237 will retract and deener ize relay 264, thus removing the winding 0 olarized relay 265 from the said series re ation with the front-bridge relay inconnector B, so that the said connector R and antecedent switches employed in forwarding the call will thereupon be restored, the circuits employed in the call being new normal'and in readiness for a new use.

Subscriber at telephone-11 replaces receiver on switch-hook while subscriber at telephone A retains his receiver of 1 If the subscriber attelephone A first replaces hisreceiver after terminating the conversation, the deactuating of the fronta bridge relayv 446 in connector E resultant thereto, will cause a circuit to be prepared for the release magnet of said connector E and the ound removed from the release trunk so t e antecedent. switches Q, N, J and LS will restore, the said connector E remaining in seizure, since the retardation coil 271 is still in series with the back-bridge relay 442. The winding of the polarized relay 265 is still in series with the front-bridge relay of connector B, so that the replacing of the receiver at telephone A produces no operative efi'ect beyond connector E.

back-bridge relay of connector R will deactuate to restore the direction of current traversing the winding of polarized relay 265 so that the relay 267 will be deenergized and thereby removethe retardation coi 271 from the bridge,

winding of the polarized relay 265 is still in so that the back-bridge relay '442 in connector E will deactuate. The

series with the front-bridge relay in connector B, so the latter said connector is still in seizure of the line leading to telephone A.

When the back-bridge relay 442 in connector E deactuates it closes the obvious circuit for the release magnet of connector E to operate to restore said connector E. This will remove the ground from conductor 211,

1 so that armature 237 will retract and deenergize relay 264, thus removing the winding of the polarized relay 265 from the said series relation with the front-bridge relay in connector R, so that the said connector R and antecedent switches emplo ed in forwarding will thereupon be restored: the circuits employed in t e connection being now normal.

Restoration of impulse sending apparatus circuit for relay the wipers'thereon to the position drawn.

Ground from armature 567 will be applied through wiper 572 and through the interrupter armature 547, causing the shaft 533 go restore the wipers thereon to the position rawn.

Calling party abandons the call while forwarding impulse train'is being sent grounded there is no ground on bank ter-* minal 412 and multiples thereof to bar the line leading to tele hone A against seizure, so that the line lea therefore become immediately seized by a. connector of the group containin connector E before one or both of the shalts 552 and 583 of elements NO and DF restore to'the drawn position. This is having in mind that at the time conductor 211 is ungrounded, the conductor 25 may still constitute ground due to the slow-releasing release relay concerned not yet having deactuated. This will cause relay 209 to momentarily actuate the cause armature 210 to apply ground to conductor 211. However, the conductor 211 may being to telephone A may armature 511 may come-finally ungrounded before the elements NO and DF have had time to restore. I

In order to revent the relay 515 from being reactuate responsive to a new seizure of the line leading to telephone A until the latter said elements have restored to normal position which said actuation would vitiate the call starting the impulse train prematurely, w ierein the proper train may not be sent,.the circuit energizing relay 515 cannot be closed until the wi ers of the latter said elements have restore so that ground from be applied through wiper 513 and its normally enga ed bank termina and the normally engaged ank terminals cooperative with wipers 536 and 539.

Line leading to telephone A encountered busy when call is forwarded thereto If the line leading to telephone A is encountered busy when the call primarily directed to telephone A is forwarded thereto, the busy tone applied to the talking conductor in connector R will pass over the lower talking conductor'to conductor 13, spring 201, armature 202, condenser 282, armature 270, tone condenser, armature 273, conductor 439, wiper 425, ringing tone condenser 445, audible to the subscriber at telephone A, having in mind that this tone will be particularly distinguishable during the silent ringing 'periodswith respect to generator G, since there will be a ringing generator (G) tone audible during the live ringing periods.

Unsetting 0 the line leading to telephone A so calls irected thereto will not be forworded The set condition referred to will endure until acall is responded to by the'subsc'riber at telephone A wherein a conductive path is included in series with the windings of magnet 242, energized from the ring-cut-ofl' relay 438 and back-bridge relay 442 of a connector as E. That is, a subscriber may return to his telephone and if on call comes to it he will answer forwarding apparatus, but if no .call comesiu he can leave again with the forwarding apparatus still in its set condition, notwithstanding that he may have made outgoing calls from his telephone.

Forwarding calls to an attendants position provided (for answering calls forwarded when ran om lines are called In the foregoing descriptions the calls to a specific telephone ne leading to telephone A were forwarded'to telephone A. It will be clear that random lines may have the'same cross connections in the respective impulse transmitting devices so that calls may be forwarded from any number of lines to the telephone A. Moreover, a roup of lines num- 05 her 33241 leading from the group of connecplace of extending to the l 563 will be moved to it and there y unset the 7 ing the conversation between t tors containin connector B may be used so 1 plurality of ca ls may be received by the subscriber At on a corresponding plurality of telephones or on an attendant s switchboard, for examp e. Again, a group of trunks leading from selector H ma extend to an attendants switchboard. this latter group is assumed to be in the second bank level, in oup of connectors containing connector R, t e cross-connecting iumpers 561 and 562 correspondin to the set two digits will be omitted, and in that event the conductor leading to bank terminal bank terminal 574. Of course, the jumpers on the cross-connecting rack may be changed from time to time as desired, so that calls directed to the corresponding telephone line will be forwarded to any desired telephone number.

Pause between series of the impulse train Due to the slow-releasing characteristic of therelay 523, after it actuates to terminate a digit series, a predetermined time will ensue before it deactuates to enable the next series.

Modification of circuits to disable the line em tension to telephone A as soon as the last imgalse of the forwarded train has been sen Fig. 9 shows a modification of the circuits.

in Fig. 2, introduced as indicated by the dotted section lines a, b and 0, so that when relay 264 actuates when the forwarding impulse tram has terminated, the extension to telephone A is cut oil by relay 264 and the bell at telephone A will cease to ring. This arrangement thus prevents the forwarded extension (to telephone A) from being intruded upon by the subscriber at telephone A after the forward extension is completed, and it also cuts off the leg to tele hone A dur- As d A, e. telephone Preferred modification which disables subscriber at tele hone A from intruding only after subscri er on line finally called is sponds Another modification of the circuits of Fig.

2 and which is the preferred one, is shown in Fhg, 10, introduced as indicated by the dotted sect on lines a and d, so that when the relay 267 actuates upon theresponse at the telepiionet Akthe leg leading to telephone A will cu o Modification of circuits to denote b distincthe tone audible in telephone when aoall is initiated whether "line is or is not set for forwarding Y Fig. 11 shows a preferred modification of the circuits in Fig. 2 involving the addition of an extra spring 290 and make and break cooperating contacts on the relay 246. A specific tone source FT is added. It will be clear that when the relay 246' is locked, and

I; the line leading to telephone A is thereby set so that calls directed thereto will be forward ed to telephone A, the tone source F'I will be substituf ed for'tone source ST to armature 217 on relay 220.' Thus, if the subscriber removes his receiver as the switch-hook after setting his line for forwarding he will per-.

ceive thespecific tone from source FT indicative that the setting is made. The tone re-.

ceived will also prompt him-of the condition when initiating an actual call.

'Meansjor uneetting the apparatus so calls will not be thereafter forwarded have the said set condition of his line effaced, so that calls will not be responded to if he does not choose to do so from his telephone A, be may call his own telephone numor from some other telephone ofhis group, perhaps, but not from telephone A (because to initiate a call from telephone A will bar his corresponding line against seizure), and when the bell of telephoneA starts ringing remove the receiver thereof from the switchhook and thereby unlock the relay 246, in the manner before described wherein the windings of the magnet 242 energized in series with telephone A on incoming calls when the relay 246 is locked. Of course, the subscriber at telephone A may alternatively call some subscriber, perhaps the subscriber of telephone A and reporthis 'return'and request that his line (leading to telephone A) be called so that he may respond to the call and thereby unlock the relay 246..

With reference to the last foregoing paragraph, it will in most cases not be desired to directively unset the forwarding apparatus as any call made to the line leading to telephone A will be responded to on the latter B5 The modification of Fig. 2 shown in Fig.

said line before it has been forwarded to telephone A and this will unlock relay 246. In case the subscriber of telephone A again leaves wherein no call has been responded to by him since setting the relay 246 the set-up condition still endures. There is no means for a party at a telephone other than at telephone A to unlock the relay 246, unless it be the central ofiice attendant manually unlocking relay 246 by tripping dog 248.

. Modification of unlatohing magnet 6 changes the winding on magnet 242 in Fig. 2 to a simple winding and the shielded core to a simple core. The windin taken from the magnet 242 are placed on to core of the relay 601'. The core of the latter said relay is shielded by a copper tube to make it unresponsive to alternatin or ringing current from the source G. T e ma at 242 is then energized in a local circuit 0 the relay 60. The magnet 242 requires considerable energy to operate its dog to unlatch the relay 246, so that a relatively few terms of windings on the relay 601 will sufiice, as compared to the num ber-of turns required where the two wind- UommeroiaZ embodiment It will be noted, that in the commercial embodiment of the present invention, sets or units of'equipment as shown in Figs. 2 and 5 ,(in view of the preferred embodments mentioned) will be rovided in sufiicient number at the central 0 cc. Then any subscriber re questing to be supplied this special service will have such a unit cross-connected into his line as indicated by the jumpers joining the respective terminals a'-a", b'b, cc", n,- l n, flzll gl gll,'hl -hll n'-n". That is, i no special unit as contemplated by the present invention is to be emp oyed, the jumpers shown joining the last said sets of terminals will be removed and jumpers or tie conductors inserted between The subscriberobtainin the service contemplated by the present invention wherein callswill be forwarded to a predetermined line ofthe exchange when desired, will perhaps pay a monthly rental or other consider-- ation for the special service provided for him, and this charge may also com rehend the number of calls forwarded as indicated by themeters M and M.

While only the first line of the group of three is shown arranged for forwarding, it will be clear that all the lines may be so arranged by the use of like circuits, having in mind that if the second line of the group is thus equipped the circuit through the spring 230 will be permanently closed. And, if the third line of the group is thus arranged the circuit corresponding to the last referred to for the second line of the group will'also be permanently closed. The circuit for the third trunk corresponding to the last re'-' ferred to will be left permanentlyopen under the condition of being arranged for forwarding calls directed to it.

Where the term relay is employed in the subjoined claims, this term is to be understood as referring to any electro-magnetical- 1 operated circuit-switching device, such fbr example, a wiper step-by-step switch.

Having set forth an exemplary embodiment of the present invention, it will beunderstood that the invention is ca able'of modification and s ial use within t e scope of the subjoined c aims.

I claim I 1. In a telephone system, a calling line, a first called line, switch apparatus for extendin a call from said calhng line to said first ca ed line, a second called line, automatic switch mechanism, a manual switch on said first called line, and means the operation of which is predetermined by an operation of said manual switch for predetermining whether said automatic switch mechanism will 0 rate to forward the connection from the ca ling line to said second called line responsive to efiectin connection from said calling line to said rst called line wherein rtion of said first called line forms a a fifii of the connection to said second called 2. a telephone system, a movable switch terminal, a first called line, a fixed terminal of said line cooperative with the movable terminal, a second called line, a relay, automatic switch mechanism, a manual switch on said first called line, means controlled over a talking conductor of said first called line for operating said relay and for retaining it operated res onsive to the operation of the manual switch, means for setting said movable terminal on the fixed terminal to thereby efiect connection from the movable terminal to said first called line, and means dependent upon said relay being operated when the movable terminal is set upon the I fixed terminal for causing said automatic switch mechanism to operate to link a connection forward from said fixed terminal to said second'called line wherein a portion of sa dfirst called line forms alink of the connection to said second called line.

3. In a tale hone system, a movable switch terminal, a ed terminal cooperative with said movable terminal, a directive device, switch mechanism, a called line, a relay, means for energizing said rela over. a talking conductor of the called line to set the relay, and means operated responsive to setting said movable terminal on said fixed terminal only if said relayhas been previously set for causing the directive device to operate the switch mechanism to link a connection from the fixed terminal to the called line.

4. In a telephone system, a calling line, a first called line, a first automatic switch mechanism for linking a connection from the calling line to said first called line, a relay, means controlled over a talking conductor of the called line for energizing the relay to set the relay, a second called line, a second automatic switch mechanism for linking a connection from the said first called line to said second called line, and means the operation of which is determined by the set condition of said relay only if the aet'condition is existent at the time said first called line is connected to it for forwarding said connection by operating said secon automatic switch mechanism to com lets the connection to said second called us wherein both said mechanisms are links of the connection to the said second called line.

5. In a telephone system, a calling line, a first called line, a first automatic switch mechanism for linking a connection from the calling line to said first called line, a relay, means controlled over a talkinglconductor of the called line for energizing t e relay to set the relay, a second called line, a second automatic switch mechanism for linking a connection from the said first called line to said second called line, means the operation of which is determined by the set condition of said relay only if the set condition is existant at the time said first called line is connected to it for forwarding said connection by operating said second automatic switch mechanism to com lets the connection to said second called hne wherein both said mechanisms are links of the connection to the said second called line, and means controlled over said first called line forunsetting the relay 6. In a telephonesystem, a calling line, a first called line, a first automatic switch mechanism for linking a connection from the calling line to said first called line, a relay, means controlled over a talking conductor of the called line for energizing the relay to set the relayila second called line, a secon automatic switc mechanism for linking a connection from the said first called line to said second called line means the operation of which is determined by the set condition of said relay only if the set condition is existant at the time said first called line is connected to it 'for forwarding said connection by operating said second automatic switch mechanism to complete the connection to said second called line wherein both said mechanisms are links of the connection to the said second called line, and means controlled over said first called line for unsetting the relay and for thereu on efiacing the forwarded extension to sai second called line.

7. In a telephone system,1a calling line, a first called line, another line, first switch mechanismfor linkin a connection from said calling line to said rst called line, second switch mechanism for linking a connection from said first called line to said another line, a signal device on each said lines, a settin means including said first switch relay, mec anism for extending a call torsaid first called line and for thereupon causing the corresponding said signal device to operate, means controlled over a talkin conductor of said first called line for operatmg saidsetting relay before said connection is estab-' lished, and means operated responsive to extending connection to said first called line onl if said relay was beforehand set to cause sai second switch mechanism to forward the connection from said first called line to the said another line and cause the corres onding said signal device to operate whi e not disabling the operation of said signal device on said first called line.

8. In a telephone system, a calling line, a first called line, another line, first switch mechanism for linking a connection from said calling line to said first called line, second switch mechanism for linking a connection from said first called line to said another line, a signal device on each said lines, a setting rela means including said first switch mec anismfor extending a call to said first called line and for thereupon causing the corresponding said signal device to operate, means controlled over a talking conductor of said first called line for operating saidosetting relay before said connection is established, means operated responsive to extending connection to said first called line only if said relay was beforehand set to cause said second switch mechanism to forward the con nection from said first called line to the said another line and cause the correspondin said signal device to operate while not disa Im the operation of said signal device on sax first called line, and means controlledover said another line for disabling the operation of the signal device on the said first called line while maintaining connection from the calling line to the said another line wherein 'a portion of said first called line .is a link of the connection.

9. In a telephone system, a calling lme,.a first called line, another line, first switch mechanism for linking connection from said calling line to said first called line, second switch mechanism for linkin a connection from said first called line to saidanother line, a signal device on each said lines, a setting relay, means including said first switch mechanism for extending a call to said first called line and for thereupon causing the corresponding said signal device to operate, means controlled over a talking conductor of said first called line for operating said setting relay before said connection is established, means operated. responsive to extendin connect-ion to said first called line onl if said relay was beforehand set to cause said second switch mechanism to forward the connection from said first called line to the said another line and cause the corresponding said Sig-- nal device to operate while not disabling the operation of said signal device on said first.

called line, means controlled over said another line for disabling the operation of'the signal. device on the said first called line while maintaining connection. from the calling line said first called line.

of said first'called line is a link of the connection," and means controlled over the said first called line for disabling theoperation of the signal device on said another lme while maintaming connection from the calling line to 10. In a telephone system, a calling line, a

first called line, another line -firstswitch mechanism for linking connection from said calling line to said first called line, second switch mechanism for linking a connection from said first called line to said another line,

a signal device on eachsaid lines, a setting' relay, means including said first switch mechanism for extendinga call to said first called line and for thereupon causing, the corresponding said signaldevi'ce to operate,,means controlled over a talking conductor of said first called line for operating said setting relay before said connection is established, means operated responsive to extending connection to said first called line only if said relay was beforehand set to cause said second switch mechanism to forward the connection from said first called line to the'said another line and'cause the corresponding said signal I device to operate while not disabling the operation of said signal device on said first called lme, means controlled over said another line for disabling the operation of the signal device on the said first called line while maintaining connection from the calling line a -to the said another line wherein a portion of said first called line is a link 'of the connection, and means controlled over the said first called line for elfacing the forwarded extension to said. another line while maintaining connection from the calling line to the saidfirst called line.

11. In a telephone system, a calling line, a first called line, another line, first switch mechanism for linking a connection from said calling line to said first called line, second switch mechanism for linking a connection' from said first called line to said another line', means controlled over said first called line only before said first switch mech-- anism links connection to said first called line for preparing a condition for causing.

said second switch mechanism to link a connection from the said first called line to said another called line responsive only to said ponnection being linked to said first called me. I

12. In a telephone system, a calling him, a first called line, another line, first switch mechanism for linking a connection from said calling line to said first called line, second switch mechanism for linking a connection from said first called line, to said another line,

means controlled over said first called line only before said first switch mechanism links connection to said first called line for preparing a condition for causing said sec-

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