US2356846A - Telephone system - Google Patents

Description

l Aug.- 29, 1944. B. D. HoLBRooK TELEPHONE SYSTEM Filed Aug. 13. 1943 "8 sheets-sheet 1 cewoeoon Aug. 29, 1944. B.,D. HoLBRooK4 TELEPHONE SYSTEM Filed Aug, 1:5, 1945s e sheets-sheet 2 Ul wk! i i @lb M.

/Nl/ENTOR B D. HOLBROOK BY @QM A T7' ORNE Y Aug. 29, 1944. B. D. HoLBRooK 2,356,846

TELEPHONE SYSTEM Filed Aug. 13, 1943 8 Sheets-Sheet 3 ATTORNEY Al18429, 944. B. D. HoLBRooK TELEPHONE SYSTEM Filed Aug. 13, 1945 e sheets-sheet `5 NNE Bm Abw Q3 Ehh? m23 v llvok /NVENTOR By 5. D. HOLBROOK @6. M

A' TToR/VEX -ug. 29, 1944. I B. D, HOLBROQK v 2,356,846

TELEPHONE SYSTEM Filed Aug. 13, 1945 8 Slleezs-Sheelrl 6 A TTORNE V Au@ 29, 1944. B. D. HoLBRooK 2,356,846

TELEPHONE SYSTEM /NVENTOR B. 0. HOLBROOK BV @6, M

ATTORNEY f Aug. 29, 1944. B. D. HoLBRooK 2,355,846 l TELEPHONE SYSTEM 8 Sheets-Sheet 8 Filed Aug. 13, 1945 FIG. 8

MqllillI-DIIM mi): mmv-lv /A/l/ENTOR B. D. HOLBROOK Bv @P M AHORA/5v V'Patented Aug. 29, 1944 TELEPHONE SYSTEM 'Bernard D. Holbrook, Madison, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation o! New York Application August 13, 1943, Serial No. 498,465 y Claims.

This invention relates to cross bar telephone systems and has for its object to facilitate the es` tablishment of connections in such a system.

In the cross barsystem, for example, as disclosed in Patent 2,201,573, granted May 2l, 1940, to W. W. Carpenter et al., and in more detail in Patent 2,232,371, granted -February lq, .1941, to J. W. Dehn et al., each switch unit comprises one hundred contact elements which provide-junc tions between ten incomingelements and ten outgoing elements. The switches which serve the (ci. 17a-22) must know whether the wantedv line is busy or idle.

Heretofore, the twenty-block relay has extended three circuits from the marker to sets of crossconnecting terminals on the number group frame. Associated with these number terminals are two sets of control terminal strips. One set of strips y includes forty strips, one for each level of the four subscribers lines are known as primary line switches and one to seven of these switches are4 arranged in a horizontal group known as a level, ten levels of which are arranged vertically to con-- stitute a frame, four frames comprising a line choice. One subscribers line is connected to each of the incoming elements and, therefore, a choice may serve from 400 to 2800 lines, the number of switches included in a level and, therefore,

the number of lines in that level being determined by traic conditions. However, as set forth, in the above-mentioned-Carpenter et al. patent, the position of the lines on the switches is entirely independent of the directory number, and a crossconnecting frame, known as a number 'group frame, is used for directing the selection of a line when called.

In the establishment of terminating connections, a terminating sender and terminating marker are employed, the sender receiving the line4 designation from the originating equipment and transferring it to the marker. From this registration the marker rst selects a vset of crossconnecting terminals representing a group of twenty line numbers within which the wanted line number lies. Bythisselection the marker determines the number group frame on .which the' terminals of the Wanted number are mounted 40- and by means of the number group connector selects a number frame and operates a hundredblock relay yand a twenty-block relay on that frame. With the twenty-block relay operated the markerv is ready to obtain information concerning the called line. l

For the establishment of a connection to the wanted line it is necessary that the marker know the line choice Within which the line is located, the frame within the choice and the level on frames in any one choice. A second set of strips serves to identify the class of the line and the line choice. with a maximum of thirty strips to y cover three line classes and ten choices.

' When both the location of a line and its class -of service is determined and a number is assigned thereto, two of the number terminals are crossconnected to the control terminal strips in accordance therewith. The third number terminal is connected directly to the winding of the .line hold magnet and, therefore, to the sleeve of the line for determining its busy or idle condition.

With such an arrangement, therefore, the successful establishment of av connection depends upon the correctness and continuity of three cross connections, the establishment and maintenance of which requires constant vigilance.

' In accordance withthe present invention, such maintenance effort is decreased by providing means for obtaining the necessary information regarding the location of a called line over a single cross connection.

A feature of the invention is the use of alternating current for supplying the necessary information concerning the location of the line over such a single cross connection.

More specically, the single cross connection is made between a number terminal and the sleeve terminal of. the line to which the number belongs. This cross connection is used to simultaneously determine the busy condition of the line and the class of the line by means of a direct current circuit. Subsequently, alternating cur-- i rent signals individual to the choice in which the line is located are transmitted from the frame over the cross connection to the marker to control the connection of the marker with the proper line choice, after which a signal is transmitted from the marker over the cross connection to the the frame. It is also necessary to knowwhether l the wanted line ,is an individual line, a party line or one of a group of lines leading to a private l branch exchange and,`if a party line, whether frame and by way of the frame connector back to the marker to identify the level and frame on which the line appears.

A clearer understanding of the invention will be obtained from a consideration of the following description in connection with the 'drawings in which:

it is a tip or ring party. Furthermore, the markerv Fig. 1 shows schematically two number grollv relay such as relay or |20.

connectors and a portion of an incoming telelating the alternating current signals transmitted from the switch frames;

Fig. 8 shows the means for receiving and recording the alternating current signals transmitted from the marker;

Fig. 9 shows an alternative method of connecting the alternating current signals to the sleeve conductors; and

Fig. 10 shows the arrangementI of Figs. 1 to 8.

A call originated by a subscriber at substation |00 is extended by equipment at the originating oilice, not shown, to an incoming trunk circuit |0| which is connected with an idle terminating sender |03 through a terminating sender link |02. The number of the wanted subscriber is then recorded in the terminating sender |03 after which the sender operates the terminating marker connector |04 to summon an idle terminating marker, parts of which are shown in Figs. 5 to 8.

When the sender and marker have been connected, the designation is transferred to the marker and recorded on a set of registers represented by thousands relay 500, hundreds relay 50|, tens relay 502 and units relay` 503. 'I'he hundreds relay 50| indicates whether the hundreds digit is greater or less than five by operating relay 505 for digits greater than live and indicates the position of the digit in either series by operating one of five relays such as relay 504. The thousands relay 500 marks one of ten conductors such as conductor 506, which is extended to one of two relays like relay 501 or relay 500 according as relay 505 is or is not operated. Therefore, the joint operation of the thousands and hundreds register identies a group of five hundred lines by operating one of a set of twenty relays such as relays 501 and 508.

The tens register, represented by relay 502, discriminates between even and odd tens digits by operating relay 5|0 for odd digits and identifies blocks of twenty numbers by operating one of a set of ve relays, such as relay 509, which in turn operates relay 5| I. The units reister relay 503 grounds one of ten conductors, which are extended to twenty conductors, over the front and back contacts of relay 5|0.

The joint operation of relay 504 and relay 501 or relay 508 selects a number group frame by completing a circuit for a marker preference In each number group connector there is a marker preference relay for each marker and these preference relays are arranged in a chain so that only one marker can attach itself to a number group frame at a time. Assuming that the terminal of the wanted number is on frame ||4, preference relay |0 is operated as soon as the frame is idle, operating a multicontact relay which closes the necessary connections between the marker and the number frame. With relay operated, the hundred block relay ||2 is operated under the control of relays 501 and 504, there being one relay I2 for each hundred numbers included in the number groups. With relay H2 operated, twenty-block relay III is operated under the control of relays ||2 and 5H, there being one such relay for each twenty numbers in the number groups associated with the frame.

With relay ||3 operated three test circuits are prepared for each of the twenty lines having the numbers selected by that relay. .As set forth above, lines may be of three classes and a test circuit of each class is provided in the marker for each of twenty lines, the twenty-block relay, such as relay H3, extending these test circuits to twenty-sets of cross-connecting terminals on the frame ||4. lFor example, terminals IIS, ||6 and ||1 are individual to the ilrst number of the group of twenty belonging to relay |I3. When this number is assigned to a line and the class of the line and its location on the primary line switch frame is determined, the sleeve contact of the line at the primary line switch frame is cron; connected to one of the terminals H5, III or ||1. If the 'line is an individual line, the ring party on a party line or'the last line of a group leading to a private branch exchange, the cross connection will be made with terminal I I8. If the line is the tip party on a party line, the cross connection will be made with terminal I|5 and if it is a. rst or an intermediate line leading to a branch exchange, connection will be made with terminal ||1.

A similar set of terminals in the first vertical row is provided for each of the twenty lines in the group connected with` relay ||3. Each twenty-block relay has a similar vertical row of terminals, and each line is connected to the one terminal of its associated set which corresponds to the class of the line.

A subscribers line, such as line 200, when it enters the oillce, is connected to a distributing frame 20|, from which the line is extended to one of the primary line switches, for example switch 202, inaccor'dance with trafilc requirements. The line itself is connected to the line terminals 203 and 204, while individual to the line terminals 203 and 204 are the sleeve or busy marking terminal 205 and the message register terminal 206. At the number group frame, assuming that line 200 is an individual line, sleeve terminal 205 will be connected over jumper ||0 to terminal I6.

Therefore, the operation of twenty-block relay I3 closes a circuit from 48-volt central oilice battery through the winding of hold magnet 201, winding 209 of transformer 208, sleeve terminal 205, jumper ||8, number groupterminal H6, contact |30 of relay I|3, contact |3| of relay conductor |32, contact 3 of relay 600, winding of relay 62|, winding of polarized relay 630 to 24- volt battery. If the line is busy, ground from an incoming trunk circuit is connected to sleeve terminal 205 over the established connection. Relay 62| operates whether the line tested is busy or idle, but relay 630 is so polarized that it operates only if the line is busy. Similar circuits are closed for each of the twenty lines having numbers in the group identified by twenty-block relay ||3.

After the number group frame has been seized, a time interval is measured to permit all of the test relays to operate, after which ground is connected under the control of the units register to the conductor identifying the individual number in the group of twenty. Since line 200 was assumed to be the rst line in the group, the units register will ground conductor SI2,

If line 200 is busy so that relay 830 operates, a circuit is closed from ground on conductor SI2 over the left contact of polarized relay 830, contact 3 of relay 82|, to battery through the winding of busy back relay 850. Relay 650 brings about the release of the sender and marker and the transmission of a busy signal to the calling If line 200 is idle and relay 830 does not operate, ground connected to conductor 5I2 completes a circuit over the right contact of polarized relay 830, contact I of relay 62|, winding of relay 000 and battery. Relay 800 at contact 1 locks to off-normal ground and at contact 8 closes a circuit from ground over that contact, contact 2 of relay 82| to battery through the winding of relay 853 which operates to prepare the incoming trunk circuit for applying ringing current to the ring conductor of the called line. At contacts I, 3 and 5 relay 800 disconnects the test circuits from the test relays 820, 82| and 822 and at contacts 2, and 6 connects these circuits together and o'ver conductor 652 to the multifrequency receiving circuit of Fig. '1.

Fig. 4 discloses a multifrequency transmitter comprising a plurality of current sources 400 to 405 each arranged to transmit current of a different frequency than the others. Each source has an adjustable amplifier, such as amplier B06, associated therewith for transmitting current of the desired volume to the output conductor 401. The output conductors 801, etc. are connected through individual resistances to distributing racks M0 and 0I I, where individual frequencies are grouped binations. The six individual frequenciesmay be combined in groups of three to give twenty dilerent combinations to identify twenty line choices which is the maximum number of choices used in one oflice. As shown, sources 400, 60| and 002 are connected over terminal I2 and conductor M3 to line choice 0 of Fig. 2, while sources 003, 008 and |305 are connected over terminal It and conductor M5 to line choice i9 of Fig. 3. Other combinations identify intermediate line choices. It will be obvious that individual sources for generating the necessary three-frequency currents may be mounted directly on the line frames, if preferred. Each level of each frame of each choice is provided with a transformer, having a winding for each line in the level and a common winding. For example, transformer 208. which is individual to level 0 on frame 0 of line choice 0 has a winding 209 individual to line 200, windings 2I0, 2| I, etc. individual to other lines and the common winding 2I2.- Each level also has a relaysuch as relay 2 I 5 individual thereto and the signal conductor is connected in multiple over the back contacts of these relays to the common windings of all of the transformers of the choice. For example, signal conductor M3 is connected over the back contact of relay 2|5 to the common winding 2I2 of transformer 208. Similarly conductor I3 is connected over the back contact of relay 2I8 to the common winding of `transformer 2|3 and over the back contact of relay 2|1 to the common winding of transformer 2I4. It may be noted that in Figs. 2 and 3 a resistance is shown connected in parallel with the hold magnet windings to reduce the impedance of the circuit to alternating current signals. When the testing circuit above traced through winding 200 was closed the multifrequency signaling current from conductor M3 was transmitted by transto obtain a plurality of signal comf associated transformer former 208 to the testing circuit, but was ineffec- 4 tive since thel test relayslike relays 82| and 830 these high frequency curare unresponsive to rents.

The receiving circuit of Fig. 7 comprises an input transformer 10|, an amplifier 102 and an output transformer 103 connected in multiple to iilters 104 to 109 which in turn control relays 1|0 to 1I5. Each of these filters is tuned to pass one of the frequencies of sources 400 to 405. Therefore, when the test circuit is extended to conductor 852, three relays are operated which identify these three frequencies.

In Fig. '1, only simple circuits have been shown including armatures of relays 104, to 109 in order to provide the twenty circuits for operating marker preference relays at the line choice connector.- In practice, these relays would control circuits similar to those disclosed in applicants Patent 2,317,191, granted April 20, 1943, to insure the operation of a marker preference relay when and only when thecorrect number of relays is operated, together with means for measuring a time interval, and making a trouble record if an incorrect number of -relays is operated atthe end of the time.

Since frequencies from sources 400, 80| and 802 were transmitted to the test circuit, relays 'I0, 1I| and 1I2 are now operated, completing a circuit from battery at the back contact of relay 100, contacts of relays 1I0, 1II and 1|2, conductorlil, winding of marker preference relay 2I8 of the line choice 'connector belonging to choice No. 0 to ground. These marker preference relays are arranged in a chain as in the case of the number group frames so that only one marker has access to one line choice at a time. Relay 2 I0 closes an obvious circuit formulticon'- tact relay 2 I 9 which' connects ground to conductor 220 as a signal that the connection with the line choice has been completed. Ground on conductor 220 operates relay 100, which disconnects the test circuit from the choice identifying circuit of Fig. '7 and extends it to the level identification circuit of Fig. 8.

. In addition, relay 2 I 9 closes parallel circuits for operating relays 2I5, 2I8, 2I1, etc., there being one such relay for each level of the fourframes making up the choice. Each of these relays operaies to disconnect the common winding of the from the inultifrequency sources of Fig. 4 and connect it with a conductor individual to the level. For example, relay 2I5 operates underthe control of relay 2I9, disconnecting winding 2I2 of transformer 200 from conductor |I3 and connecting it to conductor `22| which is individual tolevel 0 on frame 0. This conductor extends over a contact of the multicontact relay 2|0 to conductor 222 which, in

turn, extends to the level identification circuit -oi Fig. 8.'

The level identification circuit is made up of a plurality of matching circuits 80|, 802, 803, etc. each comprising a double balanced modulator. A source of alternating current which is individual tothe market is applied through transformer 800 to conductor 1 I1 which extends to the test circuit and also extends in multiple to the matching circuit 80| and the corresponding transformers of the other matching circuits 802, 203, etc. There is one such matching circuit. for each of the levels in a line choice, that is, there are forty matchingcircuits. Current applied over conductor 1'I1 to the test circuit is transmitted from the individual winding 209to the common winding 2I2. When a level relay, such as relay 2|5 operates, it connects the common winding 2|2 of the associated transformer 206 to conductor 222 as above described. Conductor 222 is extended at this time to the output transformer 8|| of the matching circuit assigned to level of frame 0. With current ofthe identical frequency flowing in transformers 8|0 and 8| I, direct current flows through the winding of relay 8|2 and that relay operates, in turn'operating relay 8|3 to inform the marker that the Wanted line is located in level 0 of frame 0. In the other matching circuits the relay corresponding to relay 8|2 cannot operate, since alternating current is connected to only one end of the associated double balanced modulator.

For a more complete description of the operation ofthe modulator employed in the matching circuits of Fig. 8, reference may be made toPatent 2,301,961, granted to M. A. Logan on November 17, 1942. Circuits of this type may also be used for the line choice identification in place of those shown in Fig. 7.

Relay 8I3 closes an obvious circuit for the associated frame relay 8| 4 which closes a circuit from ground through the winding of relay 3|5, over conductor 8|6 and through equipment at frame 0 to the winding of relay 223 operating both relays when the frame is idle. Relay 223 prepares the frame circuit for completing a terminating call and relay 8| 5 supplies ground to the level indicating relay 8.|3 which extends this ground over conductor 8I1 to the winding of horizontal group relay 224l which in individual to the 0 level of the frame. With relay 224 operated, the operating circuits for the ten select magnets 225, 226, etc corresponding to 'the ten line junctors which serve line 202, are extended through to the marker where the marker proceeds to select an idle channeLoperates the incoming and secondary line switches and operates hold magnet 201 over the test circuit thereby completing the connection between the incoming trunk circuit 20| and line 200. Ground from the incoming trunk circuit is extended through the switches to sleeve terminal 205, holding magnet.

201 operated. The release ofthe marker following the completion of the talking circuit releases all of the relays of the line choice connector. These operations take place as described in the above identied Dehn et al. patent.

Assuming that line 23| is the tip party on a party line, the corresponding sleeve terminal 232 will be connected over jumper'233 to the terminal |33 of the associated set of number terminals. When the line 23| is called, the set of terminals including terminal |33 will be selected in the manner described for line 200. A circuit will then be closed from battery through the winding of hold magnet 234, winding 238 of transformer 2 I4, sleeve terminal 232, jumper 233, number group terminal |33, contacts of twenty-block relay ||3 and multicontact relay III, conductor |34, contact I of relay 60|, windings of relays 623 and 63| in series to 24-volt battery. If line 23| is idle, only relay 623 operates and a circuit is closed from ground through the units register, right contact of polarized relay 63|, contact of relay 623 to battery through the Winding of relay 60|. Relay 60| locks and closes a circuit from ground over its contact 8, contact 2 of relay 623 to battery through the winding of relay 65| which prepares theincoming trunk circuit to signal the tip party. Since line 23| is also located in choice 0, the selection of that choice by the circuits of Fig. '7 takes place as described for 4line 200, the common windings of transformers 208, 2|3 and 2|4 being connected in multiple to the same multi-frequency source. After relay l 2|9 operates, in turn operating relay 2|1, the common winding of transformer 2 I4 is connected to conductor 235 and thence to the matching circuit 840. Relay BIB operates to indicate that the wanted line is on level 0 of frame 3. Relay 8|! l0 operates frame relay 8| 9 which connects relay.820 to relay 236 to determine when the frame is ready for completing the call. Relay 820 supplies ground to relay 8I8 which extends this ground to conductor 82| and the windingof horizontal group relay 231 which functions to close the select magnet circuits as did relay 224. The completion of the connection takes place in the usual manner.

The operation in the case of a terminal hunt.

ing group will now be described. The rst group of terminals on number group frame |24 has been shown as constituting a single group of lines serving a single subscriber. It will, of course, be understood that such terminal hunting groups 25 may appear on any number group frame and may include any desired number of lines. Lines ,300 and 230 which are the first and an intermediate line of the group have their sleeve termi- `nals connected to the bottom terminals of the associated terminal sets on the number group frame, while line 30| which is the last line of 4the group has its sleeve terminal connected to the center terminal in the number group set.

When the number of the subscriber served by this group of lines is dialed, the marker operates preference relay |20, followed by multicontact relay I 2'I, hundred-block relay |22 and twentyblock relay |23.y When relay |23 operates it connects the sleeve terminals of lines 300, 230 and 30| over contacts of relay |2| to conductors |35, |36 and |31 respectively. Conductor |35 extends over contact 5 of relay 600, through the winding of relay 622 to the winding of relay 630 and 24- volt battery; conductor |36 extends over rcontact a 5 of relay 60|, winding of relay 624 to the winding of relay 63| and 24-volt battery; conductor I 31 extends over contact 3 of relay 6|3, winding 2f relay 625, winding of relay 649 to 24-volt batery.

n Assuming first that line 300 is idle, relay 622 operates and relay 630 does not, thereby operating relay 600. Relay 600 causes the operation of relay 653 to control the ringing of the selected line. Other operations take place as previously u described.

Assuming that only the last line of the group, that is line 30| is idle, relays 622 and 630, 624 and 63| similar relays of the intermediate test circuits, and relays 625 are operated. When .o ground is connected to conductor 5|2 a circuit is closed over the left contact of relay 630, contact 3 of relay 622, left contact of relay 63|, contact 3 of relay 624 and over similar contacts on the.4

intermediate test relays, right contact of relay 643, contact of relay 625 to the winding of relay lvl 3 and battery.

It may be noted that for a terminal hunting group having more than twenty lines so that the test circuit of the twentieth line is connected 10 to relay 626, if all of the lines in the one twenty block are busy, ground is extended to conductor 621 to control the selection of anotherblock oi lines for test, in a manner similar to that shown in the Dehn et al. patent.

2| When relay 6|9 operates it connects conductor |31 to conductor 652. The common winding of transformer 303, associated with the switch level in which line 30|,is located, is connected over the back contact of relay 305 to conductor I5 and the multifrequency source connected to terminal 4|4, in parallel with the common windings of the other transformers belonging to choice I9. Therefore a 'signal made up of the frequencies of sources 403, 403 and 405 is transmitted to the. line choice selecting equipment of Fig. '1, resulting in the operation of relays 1I3, 1M and 1|5. These relays in turn connect battery to conductor 1|8, operating marker preference relay 305.

v Relay 306 operates multicontact relay 301 which ,connects the marker with the vcircuits of line choice I9.

Relay 301 grounds conductor 220 to operate relay 100 and also operates relay 305 and the other level relays, connecting the common winding of transformer 303 to conductor 300. With relays 100 and 305 operated', current from source 800 is connected in parallel to the input transformers of the matching circuits and to the test circuit over which it extends to winding 309 of transformer 303, where it is transmitted to the common winding and over conductor 308 to the output transformer of matching circuit 302. Relay 822 therefore operates to indicate that the wanted line is located in level 9 of frame 0. Relay 822 operates frame relay 8M which tests the frame as above described. When relay SI5 operates, ground is extended over contacts of relays 8|5 and 822, conductor 823 and contact of relay 301 to the winding of horizontal group relay 3I0 and battery. The further operations of the circuits are the same as previously described.

An alternative arrangement of the frame circuits is shown in Fig. 9. In this arrangement the hold magnets such as magnet 901 have two windings, one of which is connected to the sleeve of the line switch and the other of which is connected in parallel with a resistance to the number group frame. One side of each winding is connected to conductor 902 and thence to bat-I tery. Therefore, ground over the sleeve of the connection alters the potential on the number group frame connection, to mark the line busy. In place of the multiple wound transformer such as transformer 208, two simple transformers, transformers 900 and 90|, are provided per level, one for the line choice identication and the other for the level identification. A relay 9|5 is operated after the line choice connector operates, in the 'same way that relay 2|5 was operated, to transfer from one transformer to the other. yWith relay SI5 normal, conductor 902 is connected over normal contacts of relay SI5, through one winding of transformer 900 to the 48-volt central oilice battery. The other wind-- ing of transformer 900 is connected to the appropriate multifrequency source of Fig. 4. v This source will be connected in parallel to the windings of other similar transformers associated with the same line choice. When the line choice has been identified and the connector relays operated, relay 9|5 is operated, connecting conductor 902 through one winding of transformer 90| lto battery. The other winding of transformer 90| is connected over a contact of the line choice connector relay to the proper matching circuit of Fig. 8, thereby providing a circuit for identifying the yframe and level in the manner previously described. f

It will be understood that the circuits disclosed for supplying and detecting the alternating current signals are merely intended to be typical.

.tration of a directory number in said control Alternating current signalling based on time division multiplex arrangements such as that disclosed in Patent 2,252,766, granted August 19, 1941, to W. H. 'LI. Holden, or on phase discrimination arrangements such as disclosed in Patent 2,154,886, granted April 18,- 1939, to A; E. Bachelet et al., may be substituted for the frequency discriminating arrangement employed.

What is claimed is: l. In a'telehone system, subscribers lines of a plurality of types identified by directory numbers, automatic switches, control equipment common to said lines and said switches, a set of terminals individual to each directory number, a set of terminals individual to each line in said switches, each set of line terminals including a 4test terminal, means to individualize one ofsaid number terminals with one of said sets of line terminals by connecting one of said number terminals with the test terminal of said set of line terminals, by a single conductor, means responsive to the registration of a directory number in said control equipment to connect said control equipment with 'the corresponding number terminal, and means operated over said conductor to indicate to said control equipment whether the associated line is busy or idle and to set up in said control equipment all the information necessary for operating said switches to complete a telephone connection with said line. 2.` In a telehone system, subscribers lines of a plurality of types identified by directory numbers, automatic switches, control equipment common to said lines and said switches, a set of terminals individual to each directory number, a set of terminals individual to each line in said switches. each set of line terminals including a test terminal, means to indlvidualize one of said number of terminals with one of said sets of line terminals by connecting one of said number ter-v equipment with the corresponding number terminal, and means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle, the type of said line, and the location of said line terminals in said switches.

3. yIn a. telephone system, subscribers lines of a plurality of types identified by directory numbers,

`automatic switches, control equipmentl common to said lines and said switches, a, set of terminals individual to each directory number, each said set of number terminals including a terminal for each type of line, a set of terminals individualto each line in said switches, each set of, line terminals including a test terminal, means to individualize one of said number terminals with one of said sets of line terminals' by connecting the test terminal of said set of line terminals with the terminal of said set of number terminals corresponding to the type of the associated line by a single conductor, means responsive to the regisequipment to connect said control equipment with the corresponding set of number terminals, and means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle, the type of said line, and the location of said line terminals in said switches.

.4. In a telephone system, subscribers lines of a plurality of types identified by directory numbers, automatic switches, control equipment common to said lines and said switches, a set of terminals individual to each directory number, a set of terminals individual to each line in said switches, each set of line terminals including a test terminal, means to individualize one of said number terminals with one of said sets of line terminals by connecting one of said number terminals with the test terminal of said set of line terminals by a single conductor, means responsive to the registration of a directory number in said control equipment to connect said control equipment with the corresponding number terminal, and means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle, the type of said line. and the location of said line terminals in said switches, said means comprising a direct current test circuit and a plurality of alternating current test circuits. I

5. In a telephone system, subscribers lines of a plurality of types identied by directory numbers, automatic switches, control equipment common to said lines and said switches, a set of terminals individual to each directory number, a set of terminals individual to`each line in said switches, each set of line terminals including a test terminal, means to individualize one of said number terminals with one of said sets of line terminals by connecting one of said number terminals with the test terminal of said set of line terminals by a single conductor, means responsive to the registration of a directory number in said control equipment to connect' said control equipment with the corresponding number terminal, means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle, the type of said line and the location of said line terminals in said switches, said means comprising a direct current test circuit and a, plurality of alternating current test circuits, and means t'o successively complete said test circuits over said conductor.

6. In a telephone system, subscribers lines of a plurality of types identified by directory numbers, automatic switches, control .equipment common to said lines and said switches, a set of terminals individual to each directory number, a set of terminals individual to each line in said switches, each set of line terminals including a test terminal, means to individualize one of said number terminals with one of said sets of line terminals by connecting one of said number terminals with the test terminal of said set of line terminals by a single conductonmeans responsive to the registration of a directory number in said control equipment to connect said control equipment with the corresponding number terminal, means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle, the type of said line, and the location of said line terminals in said switches, said means comprising a direct current test circuit and a plurality of alternating current test circuits, means responsive to the completion of said direct current test circuit for connecting one of said alternating current test circuits tovsaid conductor, and means responsive tothe completion of said one alternating test circuit to connect another of said alternating test circuits to said conductor.

7. In a telephone system, subscribers lines of a plurality of types identified by directory numbers, automatic switches arranged inchoices, each choice comprising a plurality of frames and each frame comprising a plurality of levels, con- 76 trol equipment common to said lines and said switches, a, set of terminals individual to each directory number, a set of terminals individual to each line in said switches, each set oi line terminals including a test terminal, means to individualize one of said number terminals with one of said sets of line terminals by connecting one of said number terminals with the test terminal of said set of line terminals by a single conductor, means responsive to the registration of a directory number in said control equipment to connect said controlv equipment with the corresponding number terminal, means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle, and the type of said line, rst sources of alternating current individual to each of said choices, other sources of alternating current individual to said control equipments, means to successively connect one of said rst sources of alternating current and one of said other sources of alternating current to said conductor, and means in said control equipment responsive' to said alternating currents to record the location of said line terminals in said switches.

8. In a telephone system, subscribers' lines of a plurality of types identified by directory numbers, automatic switches arranged in choices, each choice comprising a plurality of frames and each frame comprising a plurality of levels, control equipment common to said lines and said switches, a set of terminals individual to each directory number, each said set of number terminals including a terminal for each type of line,

a set of terminals individual to each line in said switches, each set of line terminals including a test terminal, means to individualize one of said sets of number terminals with one of said sets of line terminals by connecting the test terminal of said set of line terminals `wtih the terminal of said set of number terminals corresponding to thetype of the associated line by a single conductor, means responsive to the registration of a directory number in said control equipment to connect said control equipment with the correspending set of number terminals, means operated over said conductor to indicate in said con-A trol equipment whether the associated line is busy or idle and the type of said line, iirst sources of alternating current individual to each of said choices, other sources of alternating current individual to said control equipments, means to successively connect one` of said iirst sources of alternating current and one of said'other sources of alternating current to said conductor, and means in said control equipment responsive to said alternating currents to record the location of said line terminals in said switches.

9. In a telephone system, subscribers lines of a plurality of types identied by directory numbers, automatic switches arranged in choices,

`each choice comprising a plurality of frames and each frame comprising a plurality of levels, control equipment common to said lines and said switches, a set of terminals individual to each directory number, a set of terminals individual to each line in said switches, each set of line terminals including a test terminal, means to individualize one of said number terminals with one of said sets of 4line terminals by connecting one of said number terminals with the test terminal of said set of line terminals by a single conductor, means responsive to the registration of la directory number in said control equipment to connect said control equipment with the corresponding number terminal, means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle and the type of said line, first sources of alternating current individual to each of said sociated rst source'over said conductor, receiving means in said control equipment, means responsive to the operation of said indicating means if said line is idle to connect said receiving means to said conductor, means selectively operated by said receiving means in response to current from said rst source to establish an auxiliary connection between saidv control equipment and the corresponding choice, other sources of alternating current individual to said control equipment, matching circuits in said control equipment individual to each level in a choice, means in said control equipment responsive.to the establishment of said auxiliary connection to connect the corresponding one of said other sources to said conductor and to said matching circuits, means to transmit' the current from said other source over said auxiliary connection to the matching circuit associated with the level on which said line terminals are located, and means controlled by said matching circuit to operate said switches to complete a telephone connection with said line.

l0. In a telephone system, subscribers lines of a plurality of types identified by directory numbers, automatic switches arranged in choices, each choice comprising a plurality of frames and each frame comprising a plurality of levels, control equipment common to said lines and said switches, a set of terminals individual-to each directory number, aset of terminals individual to each line in said switches, each set of line terminals including a test terminal, means to choices, means to transmitcurrent from the asindividualize one of said number terminals with one of said sets of lline terminals by connecting one of said number terminals with the test ter-r minal of said set of line terminals by a single conductor, means responsive to the registration of a directory number in said control equipment to connect said control equipment with the corresponding number terminal, means operated over said conductor to indicate in said control equipment whether the associated line is busy or idle and the type of said line, first sources of alternating current individual to each of said. choices, a transformer for each level having a winding for each line connected to the associated test terminal and a common winding for transmitting current from the associated iirst source over said conductor, receiving means in said control equipment, means responsive to the operation of said indicating means if said line is idle to connect said receiving means tosaid conductor, means selectively operated by said receiving means in response to current from said rst source to establish an auxiliary connection between said control equipment and the corresponding choice, other sources of alternating current individual to said control equipment, matching circuits in said control equipment individual to each level in a choice, means in said control equipment responsive to the establishment of said auxiliary connection to connect the corresponding one of said other sources to said conductor and to said matching circuits, means to connect said common winding over said auxiliary connection to the associated matching circuit to` transmit the current from said other source thereto, and means controlled by said matching circuit to operate said switches to complete a telephone connection with said line.

BERNARD D. HOLBROOK.

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