DE965137C - Circuit arrangement for telephone extension systems with dialer operation - Google Patents

Description

S 2

The invention relates to a circuit arrangement for telephony auxiliaries learn systems with Wäblerbetrieb with the possibility of switching on the part of certain connection points. As connection points with external possibility come in extension η systems z. B. In addition to the attendant console, certain secondary subscribers can be considered, ins-1 > there are other so-called seam interfaces that conversations are held in the absence of the operator

ίο mediate the inquiry channel.

In known circuit arrangements, the connection takes place automatically both when mediated by the place and when mediated by the next. Each intrusion causes, even if only temporarily, a circuit-related disruption of the subscribers, whose connection path is intruded, by knocking noises. In addition, the existing connection is attenuated by the additional parallel connection of a further connection path that takes place during connection. This attenuation assumes particularly disruptive dimensions when several intrusions take place simultaneously ¹ on the same connection, for example when the same busy subscriber line is controlled by several switching stations at the same time. In the case of automatic connection, these disadvantages always occur, although in some cases a connection is not intended or even undesirable.

It has already been suggested that the subsidiary officer should be activated by a special To initiate switching action by the officer, on the other hand, the intrusion by a night station

709 533/306

automatically, so that when a connection is forwarded, the disadvantages of the automatic Intrusion occur.

In view of this, connections are disassociated advantageous, in which the activation is not automatic, but only on special switching

- the operator takes action. For such arrangements it is known that with an office transferor provided with an office voter

ίο to assign switching means after the busy test of the official voter via an activation button of the officer or during an activation incentive of a Night station · via the Spreohadern, opening up to the manned intercom in the office transmission cause.

But if there are more options between the transfer of the office and the line selector, e.g. B. Call seekers and group dialers, these are the intrusion incentives from the subsidiary officer and the night station to the line selector.

The aim of the invention is to provide such a transmission of the activation incentives with little To carry out effort flawlessly. This is achieved according to the invention in that the _. line selector reached via another dialing level Relays are assigned, which are controlled by the office transmission via the Spreohadern and the connection path to an occupied station not only for the duration of the Switching action by a placement officer, but also by a temporary switching action the night station after the connection has been established by this station up to the initiation of a further. Through the switching process.

The figure shows an example of the circuit arrangement according to the invention in use in a private branch exchange, in which external calls coming over the external line, 4L with the help of switching means of the external transmission AUe either through the place Pl or through the night exchange NVSt on the way via the call booker AS, the group selector GW and the line selector LW are conveyed to the desired secondary stable participant N 2. Only the ¹ switching means and circuits required to understand the concept of the invention are shown.

I. Incoming trunk connection,
made by the placement officer

i. Connection establishment
if there is a free participant afterwards

14 vs, windings I and II of the throttle relay D nsa i, capacitor Co, interrogation set BA, contacts 12 vs, 16 e

22, as, 26zii, voice vein 4. Stimulated by the loop formed, the call seeker AS adjusts to the same and switches the voice veins through to the group selector GW. The office loop is meanwhile held via contact 1S vs and the terminating resistor Wi2 .

The civil servant now begins with the choice of the desired Teidner number. After dialing the first digit, the group selector GW occupies a free line selector LW. Here, a not shown here occupancy relay C of the line selector is energized, which closes its contact 32 c until the connection is triggered. The selector setting is done by pulse-wise loop interruption by means of the contact nsi of a number switch or the like. The number switch closes or opens, as long as it is not in the rest position, its «.ra contacts, of which nsai the interrogation set during the dialing away-

With an incoming exchange call, the relay AR in the exchange transmission ^ LZV is excited by the ringing alternating current flowing over the speech wires 1 and 2 of the exchange line AL. Relay. 4R switches on in a manner not shown. Display means at the operator station Pl , which asks the officer to interrogate. For this purpose, the operator presses the button AT, via which the relay "AS ^{1 is} stimulated, which binds itself in a manner which is not of interest here. Relay AS opens its contacts 3 as and 5 as as well as 2OaJ and 22 a.? And closes the contacts 4 as and 6 as as well as 21 as and 23 as. The following speech loop is formed for the trunk line AL : Speech wire i, contacts 1 si, 40s, gvs, nsi, throttle Dr, contact 1 i6vs, interrogation set BA of the civil servant, contacts 11 vs, 6as, 7si, speech vein 2. After receiving the mediation order, the officer switches on the relay VS by pressing the button VT . Relay VS opens its contacts 9 vs, 11 vs, 13 vs, ii6vs and closes its contacts 10 vs, 12VS, 14VS and 15 vs. The interrogation set of the officer is now in a loop closed over the speech wires 3 and 4: ^{Speech wire 1} 3, contacts 24μ i, 21 as, 10 vs, nsi.

switches and nsa 2 at the beginning of each selection pulse series the relay E energized via its windings' I and II, which at the end of the election, after the contact nsa 2 has reopened, is delayed by short-circuiting its winding I via its own contact 18 e again. Relay E switches the loop through smoothly during each selection pulse series by closing its contact ije, which short-circuits the windings I and II of the throttle relay D. Contact nsa 3 is open during the election. The nso contacts can also be contacts of a relay which is controlled by a single corresponding contact of the numeral switch.

After pressing the AT button, the relay AS has its. Contact 117 as the throttle relay D is energized via its winding III. This has closed its contact n6d. After each series of dialing pulses during the release time of relay E

Via contact 116 d, contact Μία 3, which is closed again, and contact 19 e , a negative potential, which is used to prepare the connection and is referred to below as preparation potential, is temporarily applied to both speech wires of connection path 3/4: ■ -, 116d, / «03, ige,

17 e, 14VS, nsi, lovs, speech vein 3

Speech vein 4

This potential has no influence on the group selector GW.

After the group selector GW has switched through the ¹ Spreehadern 3 and 4 to the line selector LW , the following circuit is established for the feed relay A of the latter: +, Al, QII , 30b, fr-wire or speech wire 4, 26111, 230s, DI, DII, 14VS, nsi, lovs, 21 as, 24111, speech vein 3 or α-vein, 28 b, Q I, A II, -. In this circuit, relay A responds, while relay Q does not pick up because its windings I and II are excited in opposite directions. The windings I and II of the relay D are excited in the same direction as its winding III.

The officer selects the next digit through which the first setting movement ^{1 of} the line selector is controlled in a manner not shown here. As shown above, at the end of the series of dialing pulses, the preparatory potential temporarily applied to the speech path causes the differential relay Q to respond temporarily by shorting its winding I. As a result, however, no further switching processes are initiated. During the second setting movement of the line selector, controlled by the last digit dialing, the shaft contact 48 a: 'closes and the relay Q, which again responds briefly at the end of the dialing pulse series, binds itself via its winding III: +, QIII, 47 q, 48 w, 38 Λ -.

In the line selector, the relay V, which was previously excited via a winding not shown here, and a relay U, not shown, now drop in the order mentioned. During the release time of the relay U a test circuit is closed, in which the relay P responds when the subscriber line is free: +, 32 c, 33 u, 34z ', FII, PI, r-wire, -. Relay P blocks the subscriber connection by closing its contact 35 p , switches off relay Q by opening its contact 38/1 and switches on relay V by closing its contact 39p, which now responds periodically via: +, slow breaker LU, 40 z, 3g p, - Relay V applies alternating current to the speech path to subscriber N2 via its contact 51z 'Calling current source, 51 v, 36p, YI, α-wire, subscriber A ^r 2, bA (kr, 43z' , 37p, 42z>, +.

When subscriber X2 reports, the relay Fan speaks: +, BI, 37 p, YII, ?> - wire, Λ '2, α-wire, FI, 36p, 50z', BII, -, relay B, which includes the The initiation of queries, the acceptance of the call and the signaling to the extension officer, does not respond in this circuit because its windings I and II are excited in opposite directions. Relay Y causes relay Z to respond by closing its contact 44V: +, Z, 44 y, 39 P> - · Relay Z switches off relay V by opening its contact 40s, and by closing its contact 41.3 it forms its own holding circuit and finally switches through the speech wires by closing its contacts 45 ζ and 46 ζ. The branch officer switches off the relay AS , which returns its ¹ contacts to the rest position. The exchange line AL is now through-connected to the desired extension subscriber N2.

2. Intrusion
on busy subscriber line

The extension subscriber N2 controlled from place Pl may already be occupied. The switching operations proceed as described above until the second setting movement of the line selector LW is completed.

The test relay P does not respond during the release time of the relay U. Since contact 38 / * does not open, the relay Q falls, which is via +; QIII, 47 q, 48 zif, 3 & P, - has not tied off. On the other hand, when relay U drops out, relay B responds: +, BI, 49 u, 48 w, 3 & p, -. Relay B opens its contacts 28 b and 30 b and closes its contacts 29 o and 31 b. As a result, the incoming speech wires are crossed in the line selector, the windings I and II of the differential relay Q are switched off from the speech path and instead the windings I and II of the differential relay F are switched into the speech path. Relay F does not respond because its two windings mentioned are excited in opposite directions. Via the also closed contact 119 & and. the contacts 118 y and 120 / the busy signal Bes is switched to the winding "III of the relay A , which transmits the signal inductively to the windings" I and II of this relay and thus to the calling connection point.

The wire crossing causes a current reversal, as a result of which the relay D at the switchboard is excited via its windings I and II in the opposite direction to its winding III. Relay D puts its contacts in the rest position, in particular it opens its contact 116 d and thereby prevents further influencing of the line selector's line selector in the speech path by applying ¹ of negative potential to the speech wires via contacts nsa 3 and V) e , for example by post-dialing on the part of the investigator.

The officer now presses the intrusion key QT for the purpose of intrusion on the occupied subscriber line N 2. This applies positive potential to both speech wires: +, QT,

120 DII, 14VS, nsi, lovs, speech vein 3

DI, speech vein 4

Under the influence of the positive potential, the relay F responds via its winding II and switches by closing its contact 52 / its auxiliary

winding III a: +, Fill, 52 /, 47 g, 48 ^, 38 ^, -. The winding III of the relay F is energized in the opposite direction to the winding II. The relay therefore only remains in the response state as long as there is positive potential on the speech path. As soon as the officer releases the activation button QT , the relay drops out again under the influence of its winding III, which is now only effective, and the subsequent opening of contact 52 /. The civil servant is switched to the busy extension subscriber JV 2 via the closed contacts 53 / and 55 g as well as 54 / and 56 g and can offer this external call to him. During this time, the busy signal B is switched off by contact 120 / and the ticker signal Ti is switched on via contact 121 /, which makes the intrusion recognizable to the subscribers.

If the subscriber N2 then activates himself by hanging up, the test relay P in the line selector can now respond via +, test distributor PV2, $ jq, 34Ü, Pll, Pl, c-wire, -. By opening contact 38 />, windings III of relay Q and I of relay B are switched off. Both relays drop out. The speech wires in the line selector are switched through again directly via the contacts 28 b and 30 &, while the windings I and II of the differential relay F are withdrawn from further influence as a result of the opening of the contacts 29 b and 31 &. The further switching processes up to the renewed hanging up of the subscriber N 2 proceed as already described above. If a subscriber who is not authorized to intrude, e.g. Ni, tries to connect to another extension participant, e.g. iV2, if he is busy, e.g. B. by pressing the earth button TA located at his station during or immediately after the election, as long as the relay B has not responded and its contacts 28 b and 30 b has opened, the differential relay Q via its winding I can however, do not bind via its winding III, since winding I is excited in the opposite direction to the latter. Relay Q drops out as soon as contact 28 b opens. If earth is applied after the contacts 29b and 31 & have closed, the relay P responds via its winding II for the duration of the earth application and closes its contacts 53 / and 54 /, but no connection takes place because the contacts 55 c / and 56 g are open. A connection by unauthorized connection points is therefore made impossible in any case.

II. Incoming exchange call, mediated by the night exchange

i. Calling the night exchange and connecting it to the exchange line

If the operator position Pl is not occupied, e.g. B. during the night, a circuit for the relay N is prepared by closing the switch NT. An incoming public call, which, as * said above, energizes the relay AR , causes the relay if to respond via contact 58 ar : +, 59 s, H, 58 ar, -. Relay H binds itself via its own contact for 60 h. At the same time, the relay N is excited via its winding II: +, NT, NIl, 60Ä / 58 ar, -. Relay N prepares by closing its contacts 6 in and 62 η the connection of the connection path 5/6 for outgoing exchange calls to the night exchange NVSt , which is now responsible for the switching of incoming exchange calls. The following test circuit to the night exchange is closed via contact 66 η : +, test distributor PVx, Pill, 63ί, 65 h, P 11, 66Ji ₅ -. Relay P responds if the night switch is not busy, blocks the connection by applying plus via its contact 67 p ι and switches through the connection path "5/6 to the night switch NVSt by closing its contacts 68 p 1 and 69 p ι.

Negative potential with superimposed ringing alternating current is applied to speech core 5 via contact 71/1. If the night exchange is off, the feed relay S responds in the following circuit: - ·, 71 h, XiI, SH, Sl, voice wire 5, 61 n, 68 p i, NVSt, 69 p 1, 62 n, voice wire 6, S III, XiII, +. Relay X1 does not respond in this circuit because its A windings I and II are excited in opposite directions. Relay 6 * lets relays C τ and T respond by closing its contact 73 s. By opening its contact 59 J it interrupts the circuit for the relay H _1, which then drops out, its contacts 60 h, 65 h and η lh opens and its contact 70h closes. Relay N continues to be held via + for 60h after contact has opened. 73 ^ 74 ^CI > - ¹ ^ I. - · The supply voltage for the night exchange is supplied via contact 70 h . Relay T has switched on relay L via its winding II by closing its contact. The occupancy circuit for the night exchange NVSt runs after opening the contact 65/1 via the contacts 109 / or 115 m and 64 t. Relay Ci switches through the speech path 5/6 to the exchange line AL by closing its contacts 77 c 1 and 78 c ι.

2. Forwarding of the connection to the desired participant

After naming the desired subscriber number, the night exchange NVSt controls the desired extension subscriber, z. B. N 2 on. To do this, she presses her earth button TA and thus applies positive potential to speech wires 5 and 6. The relay X 1 now responds via its winding I and closes its contact 79 χ ι, whereupon the relay Zi responds: +, 8031, ZiI, 79 Jtr i, 107 «3, 1051/2, -. Relay Z1 prepares a circuit for winding I of relay Y by closing its contact ξ ι, which, however, remains short-circuited as long as contact 79 χ ι is closed, in other words, as long as the night exchange presses its earth button TA. If the button is released, relay Y responds as a result of the excitation of its winding I and, together with relay Z1

held: +, 823 ', FII, ZiII, FI, 8121, 107113, 105 112, -. Relay Zi disconnects the exchange line AL by opening its contacts 121 and jzi. The office loop is held via the terminating resistor Wi ι switched on by the contacts 2 ι and 8 s 1. By closing the contacts 832 ι and 8431 a loop is closed over the speech wires 9 and 10 or 7 and 8 of the inquiry path, which stimulates the call seeker AS to adjust to this connection path: speech wire 7, 851 * 3, speech wire 9, 8321, Transformer winding, LI, transformer winding, 8421, 1121, voice wire 10, 87 ^ 3, voice wire 8.

This is followed by the setting of the group selector GW and the line selector LW by means of a series of dialing pulses from the night exchange NVSt. The relay S in the exchange transmission AUe drops out impulsively during the dialing due to loop interruption and lets the relay / respond accordingly impulse-wise via its contact for 75 s : +, 114 *, II3MI, 74CI, 75J, /, ■ -. Relay C ι is via contact 72.? impulsively short-circuited, but does not drop out during the election due to the drop-out delay caused by this. Relay / interrupts with its contact 112 f impulsively the loop closed via the speech wires 9 and 10 or 7 and 8 of the inquiry path. The winding i of the relay L is short-circuited during this, as shown below, by closing the contact nsz'i.

If the extension subscriber iV 2 is free, the further switching processes in the line selector LW proceed as described above under I, 1. The subscriber takes over the exchange call offered to him by the night exchange NVSt by pressing his earth button TA. The relay B in the line selector responds via +, TA, α-wire, FI, 36p, 50W, 511, ■ -. Relay B crosses the incoming speech wires by closing contacts 29 & and 31 b. As a result of the crossing, the winding I of the relay L in the office transmission AUe, which was previously excited in the same direction as its winding II, is now excited in the opposite direction. The relay L leads its contacts to the rest position.

When the extension subscriber was unhooked, a relay M, not shown, of the exchange transmission responded and closed its contact 100 m . When relay L drops out, relay Ui responds: +, 99 1, 101I, 100m, 102112, UiII, -. Relay Ui prepares a circuit for winding I of relay U2 by closing its contact 103mi, which, however, remains short-circuited as long as contact 101I is closed, in other words as long as extension subscriber N 2 presses its earth button. If the extension subscriber releases his TA key, the relays U1 and U 2 are now energized simultaneously: +, 99 1, 103 u i, UiI, U2I, 104M2. U2II, -. Opening contact 105112 interrupts the circuit for relays F and Z1. After the relay Z1 drops out, the exchange line AL is switched through again via its contacts 1 2 1 and 731; the speech path is switched through to the speech wires 7 and 8 via the contacts 25 u ι and 27 u ι, respectively.

Relay L opened its contact 109 / during its drop-out, and contact 115 m was opened ^{when the extension subscriber Λ Γ 2 reported.} The occupancy current for the night exchange NVSt has thereby been interrupted. Relay P1 drops out and switches off the night exchange from speech path 5/6 by opening its contacts 68 p 1 and 69 p 1. Thereupon the feed relay S drops out in the transfer of office and closes with its contact 72.? the relay C ι briefly, which also drops out. The speech path 5/6 is switched off by opening the contacts 77 c ι and 78 ei. The opening contact 74ei causes the relay N to drop out.

3. Intrusion on the busy subscriber line

When the extension subscriber N2 is dialed by the night exchange NVSt, the delayed relays Vi and V2 of the exchange transmission AUe are energized during each series of dialing pulses. Relay Vi is switched on impulsively via contact 891 of the relay / and is maintained over the pulse pauses as a result of the self-shared drop-out delay due to the short circuit of its winding I via its own contact go ν ι 9 ". Via contact 91 i of the relay / the relay V2 is switched on and until Drop of relay Vi held via its contact 92271. Relay Vi switches the loop 9-10 smoothly through with its contact 115 ν τ during the selection.

At the end of each dialing pulse series, the relays Vi and V 2 drop out in this order and, via their contacts 93 ^ 1 and 952/2, cause a temporary negative potential to be applied to the speech wires of the connection path 9/10, determined by the release time of the relay xoo V2: -,. 96 p, 97 n,

84s ι, 115 vi, 8321, speech vein 9 II2J, speech vein 10

This preparation potential excited, as in I, ι stated above, the differential relay Q of the line selector LW is located after the second adjustment movement of the line selector on its winding II relay Q above +, QHI, 47 g, 48 w, 38 / "-. And remains in the working position, since the relay P cannot respond due to other occupancy of the subscriber N 2. After energizing of the relay U in the line selector LW relay B responds: +, 51, 49M, 48W, 38p, -. Relay 5 crosses the incoming speech wires in the line selector and, as described earlier, switches the windings I and II of the relay Q from the speech path by opening its contacts 28 b and 30 & and instead by closing its contacts 29 b and 31 & the windings I and II of the differential relay F in the same.

If the night exchange NVSt wishes to access the busy subscriber line N2

709 533 '=

switch, it dials any number, eg »i«. This post-selection does not trigger any further switching processes via relay A of the line selector, since the selector is already set. On the other hand, via the chain of contacts 93WI and 95 ^ 2 of relays Vi and V'2 in the exchange, as already shown above, a short voltage pulse is again applied to the speech wires of the connection path 9/10, through which now the differential relay F via its Winding I is excited. Since the excitation via winding I is in the same direction as the excitation of winding III of the relay that occurs after contact 52 / is closed, relay F binds itself in contrast to connection by applying positive potential, in which winding III acts as a counter-winding to winding II, now about its auxiliary winding III. The night exchange is now switched to via the contacts 53 / and 55 q and 54 / and 56 g until further switching operations are initiated on the subscriber N 2 .

In order to take over the exchange call, the subscriber Λ'2 releases his connection by hanging up, whereupon the relay P in the line selector responds, as already stated, and by opening his contact 38 / »the circuit for the relays F and Q and for the winding I des Relay B interrupts, whereupon these relays drop out and the crossing of the speech wires in the line selector is reversed. The subscriber N 2 hangs up again and takes over the exchange call by pressing his earth key TA , as described under II, 2.

As can be seen, in the case of a normal query between extension subscribers who are not authorized to intrude, in which the relays Vi and V 2 also respond in the exchange transmission AUe in the course of the dialing process, no intrusion can take place by applying negative potential to the query path 9/10, because, itself if contact 97 η is closed during night switching, but contact 96 p is open, which, due to its dependence on the switching of the night switching center NVSt , expressly marks the call to be switched on the inquiry path as an incoming exchange call.

Claims (1)

Patent claims: i. Circuit arrangement for telephone extension systems with dialer operation and transmission of the intrusion incentives of the extension officer and the night station from the office transmission to a line selector reached via a further dial, characterized in that this line selector (LW) relays (F) are assigned which are from the office transmission (all) via the speech wires are controlled and the connection path to an occupied call station is switched through not only for the duration of the switching action of an operator (PI), but also through a temporary switching action of the night station (NVSt) after the connection has been established by this station until another switching process is initiated. 2. Circuit arrangement according to claim 1, characterized in that the same switching means (F, Q) of the line selector (LW) perform both the temporary and the permanent connection. 3. Circuit arrangement according to claim 1 and 2, characterized by a differential relay (F) of the line selector (LW), the tepotential corresponding to the respective on switch (e.g. plus or minus), either only maintains the activation status as long as how the switching potential is applied, or it beyond the duration of the potential application can exist until further switching operations are initiated. 4. Circuit arrangement according to Claim 1 and 3, characterized in that the differential relay (F) switches on an auxiliary winding (III) which acts as a holding winding when the one differential winding (I) is excited and as a counter-winding when the other differential winding (II) is excited. 5. Circuit arrangement according to claim 1 and 4, characterized in that the differential relay (F) continues via its auxiliary winding (III) beyond the duration of the potential application when negative potential is applied to the connection path for connection. 6. Circuit arrangement according to claim 1 and 4, characterized in that the differential relay (F), when positive potential was applied to the connection path for connection, is returned to the rest position by the influence of its auxiliary winding (III) as soon as the potential is removed. 7. Circuit arrangement according to claim 1 and 3, characterized in that the differential, Renz relay (F) is switched by an excited to a busy subscriber line relay (B) of the line selector (LW) in the passageway (b 29, 31 b). 8. Circuit arrangement according to Claim 3 and 4, characterized in that the differential relay (F), in particular its auxiliary winding (III), is controlled by a further differential relay (Q) which prepares the connection. 9. Circuit arrangement according to claim 1 and 8, characterized in that the further differential relay (Q) during the setting process of the line selector (LW), in particular at the end of the respective dial pulse series, by temporarily applying a preparatory potential (z. B. minus) to the connection path is excited and binds to a holding winding (III) until further switching processes are initiated. 10. Circuit arrangement according to claim 7 and 9, characterized in that the preparation potential from the connection path is switched before the differential relay (F) is switched on in the same. ii. Circuit arrangement according to Claims 1 and 8, characterized in that the further differential relay (Q) is in the connection path and is switched off (28 fr, 306) by a relay (B) of the line selector (LW) which is excited when the subscriber line is busy. 12. Circuit arrangement according to claim 8 and 9, characterized in that the auxiliary winding (III) of the differential relay (F) is dominated by a chain circuit consisting of its own contact (52 /) and a contact (47g) of the further differential relay (Q). 13. Circuit arrangement according to claim 1, 3 and 8, characterized in that the connection of the speech path takes place when switching on via a chain connection of contacts (53 / -55 q, 54 / -50 q) of the two differential relays (F, Q) 14. Circuit arrangement according to claim 1. 2 and 3, characterized in that the connection points (Pl, XVSt) which are authorized for connection control the switching means (F, Q) of the line selector (LW) via the speech path. 15. The circuit of claim 1, 9, 10 and 14, characterized by the aufschalteberechtigten connection points (PL NVSt) controlled switching means (nsa-E, vinyl V2) of the operator position (Pl) and the transmission of office (AUe), which during the On the house of the connection between these stations and an extension subscriber (N 2), especially at the end of the individual dialing pulse series, temporarily apply a potential that prepares the connection (e.g. minus) to the speech path. 16. Circuit arrangement according to claim 14, characterized in that the connection takes place by post-election on the part of the night switching center (NVSt) . 17. Circuit arrangement according to claim 1, 3, 15 and 16, characterized in that when calls are switched through certain connection points, in particular night exchanges (NVSt), on the inquiry path (9/10) by the same switching means (Vi, V2) of the exchange (AUe) also the connection potential ( e.g. minus) is placed on the connection path. 18. Circuit arrangement according to claim 1, 15 and ιό, characterized in that the application of the preparatory potential and the connection potential of switching means (g6p) dominates when switching calls through certain connection points, in particular night exchanges (NVSt) on the inquiry path (9/10) that mark the call to be transferred as an incoming exchange call. Considered publications:
German patent specifications No. 436 665, 655 050, 704607; »Low current construction and operating technology«, 1932, issues 9/10, pp. 137 to 140 and 160 to 165. 1 sheet of drawings © 709 533/306 5.57