DE1043414B - Circuit arrangement for connection devices equipped with dialers for the interconnection of two or four-wire connection lines ending in transmissions in telecommunications systems, in particular telephone systems - Google Patents

Description

GERMAN

The invention relates to circuit arrangements in which two- or four-core connecting lines in Transmissions end and two connection lines via a connection device equipped with dialers are interconnected, in which the transmissions of the lines to be connected from one Supervision place are marked and the connections are switched through after setting the voters.

If only two-wire or only four-wire connecting lines are present in such arrangements, so no difficulties arise when interconnecting two connecting lines.

However, if two- and four-core connecting cables are mixed in such a system, then it must when interconnecting two unequal connection * 5 lines a special criterion are transferred so that the four-wire connection line in this assigned transmission is switched to a two-wire connection line. The sending out of a such additional criterion is for the ao Officer of the supervisory station represents an additional burden.

The object of the invention is, regardless of the type of connecting lines to be interconnected, the To relieve the official of the supervisory place. This is achieved in that the two Cores of a speech path are crossed in the connecting device and thereby response circuits for in the Connection device and arranged in the transmissions identification relays are closed.

Furthermore, the arrangement according to the invention, depending on the type of interconnected lines, the type of character transmission or the inclusion of attenuators od. Like. Allows without the Officer must also trigger switching operations.

As an exemplary embodiment of the invention, the drawings show a connection device in a control center with a hundred connection lines. All circuit single circuit arrangements for with selectors not required to explain the invention
equipped connection devices

to interconnect two in

Transfers ending two or

four-core connecting cables

in Fermelde, in particular

Telephone systems

Applicant:
Siemens & Halske Aktiengesellschaft,

Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Georg Finsterwalder, Munich,
has been named as the inventor

Tragung Ue 10 is connected to the connection devices VE1 to VEx via the line £ 10. Similarly, the other transmissions are associated with these links.

If the incoming transmission UeIO is occupied and the calling subscriber wants a connection to the connection line VL 20, a lamp lights up when the UeIO transmission is occupied at the switchboard PL , and the officer connects to the incoming line. At the same time the transfer UeIO is marked on the Markierleitung MLlO. After the

units are omitted for a better overview 40 calling participants of the officer the desired Verorden, binding direction, z. B. VL 20 has notified labeled Fig. 1 shows an overview diagram of an exemplary this transmission Ue20 and switched by operating example of the invention, while FIGS. 2 to 4, the emergency button of the compound VT is the test device PE a. show agile circuit details. In Fig. 1 of the hundred possible transmissions the selector relay WR, only three, namely the transmissions UeIO, Ue20 seeks a free connection device VE and occupied and Ue30, are shown. These transmissions can be made through this. After a connection device has been assigned, connecting lines VL 10, VL 20 and VL30 to the incoming ones arranged in this connection device are assigned. Conversely, the over-selectors W1 and W2 can be left on. A voter turns the connection lines 50 assigned to them to the incoming transmission UeIO and the outgoing transmission. As can be seen from this figure, other voters on the outgoing busy transmission Ue20 are four-wire to the transmissions UeIO and Ue20. After setting both selectors, a check is made as to whether the connection lines and a two-wire or four-wire connection to the transmission Ue30 and a two-wire connection line are connected. The over- den should. After the connection has been switched through, the

«09 678791

3 4

Testing device PE triggered and can be used for a new During the excitation of the rotary magnet WR are the

Connection establishment are occupied. Contacts 311 w and 313 w closed. About the con-

Fig. 2 shows the required to explain the invention clock 313 wr is energized relay DW :

borrowed circuit details of the transmissions UeIO, ο _j_ «q ,,. ,, r, ™ -

Ue20 and Ue30. 5 "'' ^W ' ''"

Fig. 3 shows circuit details for through-connection by closing the contact 305 dw that is still

the speech and signal wires as well as the test circuits for relays Vl that have not dropped out are re-energized:

the test relays of the voters Wl and W2 of the connection g , 395 ^ 304 ^ 1 Vl

facility VEl. '''''

In FIG. 4 the starting circuits for the voters as well as the contact 317 dw are connected to the test relay Pp , the occupancy circuit of the connecting device VE1 pulls it on when the contact is made to the reached contact. Further, Fig. 4 contains the circuit details of the switched connection device is free. If, however, as the test device PE and the one drawn to explain the figure in the figure, only the details of the operating-closed connection device required in the second step are free, then Replatzes PL. Don't put on 15 lais pp on the first step. To

With incoming assignment of the transmission UeIO tightening the relay DW is interrupted by opening the Konüber the connection line FXlO the clock 312 dw the response circuit for the selector relay WR official in a manner not shown to the speech wires. The transmission UeIO occurs when contact 313wr is opened. When it is switched on, relay DW is switched off and the Maridertaste MT10 is actuated by closing its switch. If the contact 312dw requests the selector relay WR to be switched on again (cf. current calling subscriber a connection with a via run no. 7). Furthermore, the contact 305 ^ 0 interrupts the connection line VL20 accessible subscriber, so holding circuit for relay Vl, which, however, due to its waste, the officer actuates the Maridertaste MT20 and delayed until relay DW is then again, provided that the test device PE is free and speaks . After the contact 313 wr is closed, the connection key VT speaks. By pressing this button 25 relay DW and switches on its contact 317 dw , relay Vl in the test facility PE in the following relay Pp to earth. Test relay Pp picks up on step 2 circuit: the selector arm wrl picks up in the following circuit:

1. +, VT, Vl, -. 10. +, 318ül, 317dw, Pp, iiirl (position 2), 260c-vein,

r, u c uv ο α Tz ₊₁₊ 1 α α · -ο ι · ^241c ' ^240Ä > ^H > 237M, 236md, 235 ^ 2, 233 »», by closing the contact vl the relays 30 232-mn

AlO and y420 in the transmissions UeIO and De20

energized: In this circuit, apart from relay Pp, relay

9 _u ^ nr »5ii WTM MT in / im ■ lais if the connection device F £ an. Let it be first

on the emitted by the tightening of the test relay Pp

3. +, 300z> l, MT20, ML20, A20, -. 35 routed switching operations were received in the testing facility PE. By closing the contact 306pp , the relay A 10 sets by closing its contact 15 α. 10 Relays Fl excited independently of contact 305 dw:

Earth potential to the AlO characteristic. Furthermore, - ^> 306 ** 304wl bottle

Closing the contact II0IO earth potential to the ^yp> '

Speech vein «slO laid. Via contact 14 «10, the 40 contact 309pp finally interrupts the response circuit for the speech wire ÖS'10 via the through-switch relay FD10 to selector relay WR (see circuit no. 7). Test voltage switched. Relais Pp stays above his after the relay DW drops out

Likewise, when relay A 20 responds via its contact 315pp. The contact 25β20 earth potential to the characteristic line £ 20 blocking relay Sp is switched on through contact 319pp:

and via the contact 21 α 20 earth potential to the speech 45 -jo _i_ 319 · λλ <? · λ

core aS20 laid. Via contact 24 «20 the speech '~ ^l ~' ^??>?>'

wire & S20 via the through- switch relay VD 20 with voltage After the relay Sp has been pulled , the test equipment

connected. direction PE the relays Vl, V2, Pp and Sp are attracted.

Relay Fl is formed by closing its contact. When relay H in connection setup act 304wl is pulled, one of the connection key VT independent of the connection key VT was opened by opening the pending hold circuit: Contact 240 h relay C in the response circuit of the Re-

4 4-307 »2 304z; 1 Fl ^ ^s ^ switched on. This circuit is also used

the test relay Pp of the test facility is held:

F ^OT ^ ^{becomes dBrch} closing of contact 314 »1 ₁₃ _ _{+> 3} 18ϊ; 1, 315 #, P /», wl (position 2), 260c-wire,

Relay F2 energized: 55 _{c> Hj 2} 37 ^, 236md, 235 «2, 233nn, 232m», -,

Relay C closes its contact 231c and switches

After relay F2 has responded, relay K via its windings I and II is switched on via the Kon.

clock 302t <2 the busy lamp BL at the operator station relay K picks up and closes via its contact 23Ok

switched on: 60 its winding II briefly. Relay K holds in the following

6. +, BL, 3021/2, 301 ^ :, -. Circuit:

14. +, 231c, 230fe, Kl, -.

By opening the contact 307 v2 , the holding circuit ^, _c ,,. ". Tr ₊ I ₊ oci τ, · αα δ

for relay Fl (see current flow Xr. 4) interrupted. . When this contact 251Ä is closed, the relay F1 remains attracted ^{due to a drop-out} _{delay 6 5} ^{letrelMS D1 of the waHer W1 reach} S ^t:. When relay F2 ^{responds , the rotation 1S} · +>25ik> ^250Ä > 243m2, 242 ^ 1, L> 1I, -.

The magnet of the selector relay WR is energized and the switching arm wr I The starting relay Dl switches via its contact 209il

switched one step further: the field coils Ml and M2 of the selector Wl on . the

Field coils Ml and M2 are spatially offset by 90 °,

7. +, 312ifo>, 310v2, 309 ^, 3Q8sp, WR, -. 70 and an anchor is rotatable at its axis intersection

stored, which is set in rotation by the alternating magnetic fields generated in the field coils. The rotary movement of the armature is transmitted to the voter shaft and thus to the voter arms attached to it by a gear transmission. The field coils are switched on alternately by controlled on the armature shaft contacts cam 206ml and 207 m2. When both field coils are energized, the armature is braked and the selector is stopped. The field coils N1 and N2 of the selector W 2 are arranged accordingly and are alternately excited by the motor contacts 216n \ and 217w2.

In the rest position shown, the field coil Ml of the selector Wl is excited:

16. +, 209il, 206wl, Ml, -.

The armature of the selector Wl is attracted by the field coil Ml and set in rotary motion. The control contacts 206 ml and 207 m2 arranged on the armature shaft are switched over so that the excitation circuit for the field coil Ml is interrupted and the field coil M2 is excited in the following circuit:

17. +, 209dl, 207 ^ 2, M2, -.

As soon as the armature is attracted by the field coil M2 , the motor contacts are turned over again and the field coil Ml is excited. The rotary movement transmitted from the armature to the switch arms causes the switch arms to sweep over the selector contact bank. The test relay Pl is connected to the test switch arm AI of the selector Wl via the contacts 121c and 123dl . The switching arm AI sweeps over the bank contacts in which the characteristic lines kl to MOO are switched on. As soon as the test arm kl reaches the marked line AlO, the test relay Pl picks up in the following circuit:

18. +, 15alO, M0 line, AI arm, 120wl, 121c, 123 ^ 1, 126Gr, 125Wi, Pill, Pll, -.

Via contact 201 ^ 1 of the test relay Pl , both field coils AfI and M 2 of the selector Wi are excited and the selector is stopped. By opening contact 242 ^ 1, the response circuit for relay D 1 is interrupted (cf. current flow no. 15), which as a result of a short circuit in its winding II via motor contact 206? «1 or via motor contact 207w2 and contact 201 fil of the test relay decays delayed. The auxiliary test relay PHl is excited by closing the contact 127 ^ 1:

19. +, 15 «10, AlO line, AI arm, 120ul, 121c,

By delayed by the fall time of the relay H start of the selector W2 is achieved that both selector Wl and W 2 are not simultaneously the same marked line and reach aufprüfen thereto. The fall time of the relay H is dimensioned so that the selector Wl has occupied and blocked the first marked line before the selector W2 reaches it.

To prevent relay H from responding again when relay Dl drops out, relay H is short-circuited via contact 239 * 1 of test relay PHl, which picks up before starting relay D 1 drops out. As soon as the test switching noise All of the selector W2 reaches the marked line k 20, the test relay P 2 picks up in the following circuit:

23. +, 25 «20, A20 line, All-Arm, 140 iil, 141 * 1, 143 (22, 145Gr, VteWi, P211, P2I, -.

By closing the contact 211 ^ 2, both field coils Nl and N 2 of the selector W 2 are excited and the voter is stopped. Contact 246 ^> 2 switches off the excitation of relay D 2 (see circuit no.20), and relay D 2 drops out with a delay due to short-circuiting of its winding II via motor contact 2Vanl or via motor contact 2Πη2 and contact 211 ^ 2. During the release time of the starting relay D 2, the auxiliary test relay PH2 picks up via contact 146 ^ 2 and closes a holding circuit independent of contact 143d2:

24. +, 25 «20, A20 line, All-Arm, 140« l, 141 * 1,

^14fi ' ² '

'* ^2Π

, Ρ2Ι, -.

142 * 2.147 * 2,

Contact 228 * 2 of the auxiliary test relay switches on the changeover relay Ul :

25. +, 228 * 2, Ul, -.

Relay Ul picks up and, by closing its contact 119wl, switches the hold circuit of the test relay Pl to the g-10 line. Likewise, by closing its contact 139 wl, the hold circuit of the test relay P 2 is switched to the g'20 line. The test relays and auxiliary test relays of the two selectors are then held in the following circuits.

45

12Ml, 126Gr,

125Wi, Pill 127 ^ 1, PHl '

PlI,

Contact 128 * 1 bypasses the rectifier 126GV and the contact 127 ^ i of the test relay Pl.

By switching on the low-resistance winding of the auxiliary test relay PH1 , the test relay P2 of the selector W2 can no longer test the test wire A10 via its high-resistance winding II.

When starting relay D 1 was picked up, relay H was short-circuited via its contact 238 dl , which delayed. After the delayed drop-out, relay H switches on the starting relay 2) 2 of selector W2 via its contact 247 A:

20. +, 251A, 248m2, 247A, 246 ^ 2, £ 21, -.

Via its contact 219 3,2 the starting relay Ώ2 switches on the selector W2 by energizing its field coils Nl and N2 :

21. +, 219 ^ 2, 216 »1, Nl, -;

22. +, 219cZ2, 217 »2, N2, -.

26. +, 16m10, glO-lead, gl-arm, 148Wi, U9ul, 122 * 2, 124 * 1.128 * 1, ^

PH, -;

27. +, 26m20, g'20 line, gll arm, 149W, 139al,

55 P2I, -.

PH2

It should be made up at this point that when the relay Pi? 2 responds via its contact 138 * 2, the two Test arms Al and All of the two voters were connected to one another.

By closing the contact 137iil, the incoming signal wire sAlO is connected to the outgoing signal wire sg20 'of the transmission Ue2Q via the switching arm sAI and the switching arm SgII. By closing the contact 136 «il, the incoming signal wire sk2O of the transmission E7s20 is connected via the switching arm sAII and the switching arm sgl to the outgoing signal wire sg 10 of the transmission iJelO. By closing the contact 226 ζ / 1, the pressure magnets Adm and Adu of the selectors Wl and W2 are excited. Depending on the position of the contacts 220 admJ221 adm and 222adnf

7 8

223 ad; ι either the pressure magnet for the upper & S20 is switched through in the transmission Ue20. the

or the lower switch arm set is energized: Relays FD10 and VD20 are activated via a not shown

221 aim, Ainio held second winding. By opening the contacts

28.-, 228ph2, 226ul, 225 ^ 2, ~~~ '15 «10 and 25« 20, the earth potential is determined by the

223 Λ ^{5 le} i ^do S ^en * 10 ^{un (} i ^ ² O switched off so that a voter

29. -, 228pli2, 226 iil, 225u2, - ^{a n>} - ?,. another connection device to this identification

' Ainu, 222 airi lines can no longer be checked. Relays [710 and

After switching through the voice wires through the connection relay [720, when the transmissions

Push magnets can be used to activate the interconnection of two UeIO and Ue20 and are shown in the manner shown

Vicr wire lines identifying relay VD on its io held until one of the two participants disconnects

Tighten winding I in the following circuit: trips.

30. +, 21 _ß 20, «S20 line, aSII-Axm, 135A, VDl, ^ J ^ r ^^^ J} * ^^ facility PE USk, BSI-Αττα, ÖSlO line, 14« 10, FDlO , -. relay F 2 is switched off by opening contact 314 * 1

switched, which drops out with a delay. After the delayed

In this circuit, apart from relay VD, the drop in relay F2 is activated, blocking relay Sp is activated by opening relay FDlO assigned to transmission üelO, and that of contact 320?; 2 is switched off. Relay Sp was triggered after the opening of contact 319pp ( not shown here in the transmission UeIO) in the following circuit switching processes that were held to switch through the four:

wire incoming connection line to a ^ 4. _i_ 2Zlsi> 32Ow 2 Si>

Continuing four-wire connection cable required. 20 "'>F> ■

are borrowed. In the transmission Ue20 the same after the dropout of the blocking relay Sp switches contact

Switching operations for switching through to a four-wire 303sp the busy lamp BL at the connection point PL off, connecting line by responding to the relay VD 20 and the officer can trigger the test device PE again in the following circuit: occupy to another connection device

31. +, 11 * 10, «SLO line,« SI arm, 116 *, & SII- ^{25 to} establish another connection.

Arm, ÖS20 line, 24 * 20, FD20, -. If all connection devices are occupied, m

this energizes relay C / 2 and contacts 252 «i2

When the relay Ul responded , the switchover was closed. The blocking relay Sp is then energized in the following relay U2 : Circuit energized:

32. +, 22% pii2, 2ZJuI, U2, -. ³ ° 35. +, 252 ^ 2, 261s £ - vein, xu2, Sp, -.

Relay U2 interrupts by opening its contact By closing contact 303s ^ the occupied-235m2, the holding circuit for relay C and the test relay Pp lamp BL is switched on and the officer is thereby also in the test device PE (see Stronüauf No. 13). Also shared is the fact that it cannot occupy the test device PE , when the relay U2 responds by opening the 35. When the conversation is over, the resistor 224TF is applied to the overcontact 225u2? Participants connected to the UeIO holding position first, so that the monitoring circuit assigned to this transmission occurs for the pressure magnets to save electricity (cf. current flows no. 28 and 29). If the relay Ü 10 drops and interrupts by opening its Kon relay C , the holding circuit for the test and auxiliary test (see current circuit no. 14) is switched off by opening the contact 231c relay K clock 16wlO relais Pl and PHl (see circuit no.26). After the end of its winding II falls off after a delay. Relay K of the auxiliary test relay PHl, which switches somewhat more slowly than that by opening its contacts 116 £ and 135 k test relay P1 drops out, the winding I of the relay VD is switched off by opening the contact. Relay VD keeps the test and auxiliary test relays P2 and PH2 out, however, via its winding II in the following circuit: switched (cf. Stronüauf no. 27). By opening his

⁴⁵ contact 228ph2 , the test relay PH2 interrupts the

όό. -ι-, U »pti &, mvA, VViI, -. Holding circuits for the pressure magnets (see current flow

Via the contacts 111 £ and 113 £ and the numbers 28 and 29), for the changeover relays Ul and U2 (cf.

closed contacts 133vd and t34cvi become the circuit no. 25 and 32), which drop out with a delay, and the

Speech wires aElQ and bElO for incoming speech-hold circuit for the relay VD (cf. circuit no. 33).

Alternating currents from the direction 20 with the speech wires 50. Due to the drop in the pressure magnets, the

aS20 and 6S20 interrupted for outgoing alternating speech currents in speech cores. The signal wires are after

Direction 10 connected. Furthermore, the delayed drop by opening the contacts 136 «i 1

115 k * md 117 k and the contacts already closed and 137 «1 open. After the relay U2 has dropped

129rif and 131vd the voice wires aE20 and bE20 for the starting relays Dl and D2 via their windings I ia

the incoming speech alternating currents from the Rieh- 55 excited the following circuits:

device 10 with the speech cores aSlO and & S10 for ab- _{36 + 245 2} ^ _{u2 242fl DU}
outgoing alternating currents m direction 20 connected.

After the relay K has dropped out, the transmission is 37. +, 249k », 248m2, 247ä, 2A6p2, D2I, -.
ΓίίΙΟ connected through a four-wire with the transfer Ue20. 60 By closing contacts 209il and 219i22,

After separating the holding circuit for relay Pp (see. The voters PFl and W2 started and turn their

Circuit no. 13), this drops out and returns the shut-off switching arms to the rest position. Reached the voter

the test facility PE . By opening his Wl its rest position, then the rest position

Contact 306pp is switched off relay Fl, which after closed contact 202mn and the contact 204c

his delayed fall by opening his contact 65 energized both field coils Ml and M2 and the voter

300rl relay .410 (see circuit no. 2) in the over-stopped. By opening the contact 245 mn the

tragtmg UeIO and relay .420 (\ -gl. current flow no. 3) in the excitation of the starting relay Dl switched off, which as a result

the transmission Ue20 switches off. After dropping this short circuit of its winding II drops off and the delayed

Both relays, the voice wires 0SIO and ÖS 10 are switched off when the two field coils are excited. The voter

of the transmission UeIO and the speech wires äS20 and 70 W2 is when the rest position is reached by the in this

Closed position contact 212mm and contact 214c stopped by energizing both field coils. At the same time, the starting relay D 2 is switched off by opening its contact 249 nn, which drops out with a delay.

After both selectors have reached their rest position again, the occupancy circuit is switched through via the 260c wire (see circuit no.10) for this connection device via the closed rest position contacts 232mn and 233 nn , and the connection device can be reassigned.

If the transmission Ue 10 is occupied again and the subscriber connected to the transmission wants a connection to the subscriber connected to the transmission Ue30, the same switching processes as described above take place with the following exception: After energizing the pressure magnets (cf. 28 and 29) can not address relay VD in the connection device VE 1 and the relay VD 10 (cf. circuit no. 30) in the transmission UeIO , since no counter potential is connected in the transmission Ue30. Since relay VD 10 does not pick up in the transmission Uc 10, the incoming four-wire connection is switched through two-wire in a manner not shown here via the speech wires aE 10 and bE 10 . In the connecting device FEl, after the relay K has dropped out, the speech wires aE 10 and bE 10 are connected via the switching arms aEl and bEl, the contacts 111 k and 113 k and 130 vd and 132 vd via the switching arms aEII and bEII with the speech wires aE 30 and E30 tied together. The connection is thus continued from the transmission Ue 10 via the connecting device FE1 and further via the transmission Ue30 only in two-wire fashion.

As can be seen from the exemplary embodiment, after the pressure magnets have been tightened and before the relay K drops out, the speech wires aE of one transmission and bE of the other transmission, and vice versa, are connected to one another. About this so connected speech wires can be given in a similar manner as they were for the interconnection of a four-wire with a two-wire or a four-wire with a four-wire connection line, identifying the type of transmission systems used, such. B. the type of character transmission, namely audio frequency signals or direct current signals. In addition, these characteristics can be evaluated for switching on attenuators to adapt the interconnected connecting lines.

Claims (8)

PATENT CLAIMS: 1.Circuit arrangement for connecting devices equipped with voters for the interconnection of two or four-wire connecting lines ending in transmissions in telecommunications, in particular telephone systems, in which the transmissions of the lines to be connected are marked by a supervisory station and the connections after setting the voters to the marked transmissions are switched through, characterized in that the two wires of a speech path are crossed in the connection device by a switch relay (K) and thereby response circuits for identification relays (VD, VDlO, FD20 ) arranged in the connection device (VE) and in the transmissions (UeIO to JJe30) ) are closed. 2. Circuit arrangement according to claim 1, characterized in that the switch relay (K) crosses the wires of a speech path (aS, bS), preferably the transmission branch, in the connecting device which is only used with four-wire connecting lines, and via these wires response circuits for identification relays (VD, VD10, VD20) closes, which are arranged in the transmissions (UeIO, UeIO) for four-wire connecting lines and initiate a four-wire through-connection of the connection. 3. Circuit arrangement according to claims 1 and 2, characterized in that the holding circuit for the changeover relay (K) characterizing the wires of a speech path is opened after switching through the speech wires (231c) and the response circuits for the identification relay in the during the delayed fall of the changeover relay Connection facility and in the transmissions are closed. 4. Circuit arrangement according to claims 1 to 3, characterized in that the identification relay in the connection device and the transmissions after the changeover relay has dropped over a second winding can be held. 5. Circuit arrangement according to claim 2, characterized in that when a four-wire (iJelO) and a two-wire (Ue30) connection line are interconnected, the identification relays in the connection device and in the transmission of the four-wire connection line do not respond and the connection from the transmission of the four-wire connection line via the Connecting device is switched through with two wires. 6. Circuit arrangement according to claim 1, characterized in that one by crossing the wires Speech path, preferably the receiving branch, response circuits for arranged in the transmissions Evaluation relays are closed, which determine the type of systems connected together via the lines, z. B. public telephone network or private branch exchange, identify. 7. Circuit arrangement according to claim 6, characterized in that one by crossing the wires Speech path, preferably the receiving branch, response circuits for arranged in the transmissions Evaluation relays are closed, which determine the type of signals transmitted over the lines, e.g. B. audio frequency, Indicate inductive or direct current signals. 8. Circuit arrangement according to claim 6, characterized in that by crossing the wires of the Speech path, preferably the receiving branch, response circuits for arranged in the transmissions Evaluation relays are closed, the activation of attenuators depending on the cause interconnected lines. For this purpose 2 sheets of drawings © 809 578/91 11.5 »