Patent GB-513544-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M3/60
Filed: 1938-04-12
Abstract: 513,544. Semi-automatic exchange systems. SIEMENS & HALSKE AKT.-GES. April 12, 1938, No. 11235. Convention date, April 17, 1937. [Class 40 (iv)] In a system in which all calls initiated by the subscribers of a number of offices U1-U4 arranged in a chain are established under the control of an operator at a main office HA and in which main office subscrbers may establish calls to the chain-office subscribers without the help of the operator, a call initiated by one of the chain-office subscribers does not busy the route over which it reaches the operator until she answers it. A call in the, opposite-direction can thus be established by a subscriber such as Tn10 in spite of the waiting call which, however, remains stored and becomes effective when the subscriber Tn10 clears. In a modified arrangement, the chain-office subscribers get exclusive use of the route independently of the operator, but are prevented from getting control for a definite interval after the release of the junction from a previous call. This inhibition may be effective only when the previous call was one originating in the chain system. In the system shown, each of the offices U1, U2 has a single finder-connector link and junction and each of the offices U3-U4 has two similar links and junctions. Reference is made also to the association of a calling link with an idle junction by a hunting switch. Calling operator from office U1. Subscriber Tn1 operates his magnet to energize his line relay A(i) which locks over A(ii) in series with a common relay An. The latter, if the link circuit is idle, or when it becomes idle, energizes Mt1 which connects battery to the wire a1 of the junction to energize the junction line relay A2(i) at office U2. A2 locks up over its winding (ii) and the signal is forwarded from office to office if the necessary junctions are, or when they become, idle in a similar manner. At offices U3, U4, there is a choice of junctions. If that associated with the link shown in Figs. 5, 6, for example, is busy, C30 is energized and the calling signal is forwarded over the other. The relays Mt1, Mt2 which apply the signal to the junctions are released immediately, afterwards by H1, H2. At U3, U4, however, the signal is applied by H3, H5 and cut off by H4. H6, which hold H3, H5. The various line relays remain locked up and that, A5, at the main office lights the calling lamp AL. Reply by operator. When the operator plugs in, tne sleeve relay C50 energizes H7 which releases A5 to extinguish the calling lamp and marks the junction busy to the automatic switches. C50 also connects battery over Dr9 to the wire a4 of the junction to cause the operation of I4, C40 at office U4. Operation of ringing key R (with answering key Ab thrown) energizes B5 which applies battery over Dr10 to the wire b4 of the junction. This energizes E4 in office U4, whereupon the finder driving magnet DAS4 interacts with relay R4. When the calling junction is reached, test and switching relay P4 pulls up in series with cut-off relay C4 and relays A4, H5, H6 are released. Relay Q4, which is energized by P4, energizes the final selector driving magnet DLW4, which interacts with H40 until the switch reaches the position marked over wiper as5 and terminal (1) of the call finder, whereupon H40 is held steadily. P4 also connects battery over Dr7 to the wire a3 to operate 13 at office U3 and battery over Wi15 to the wire b3 to operate E3. As a result the call finder at U3 hunts for the junction a2, b2 and the final selector moves to a corresponding position in the same way as the corresponding switches in U4. Battery is connected to both the junction wires when the finder switching relay pulls up to energize E2, I2, C12, C20 in U2. The call finder here hunts as in the other offices but the final selector remains stationary. When the finder switches through, battery is connected over a relay X2 to a1 and over a resistance to b1. At the originating office U1, I1 energizes C1, C10 and E1 energizes H10. The finder hunts for the calling line under control of P1 which pulls up to stop the switch in series with the calling cut-off relay C, and H1, H10 are released. Ringing current is applied to the calling line by W1, while the ringing key is operated, until the calling party removes his receiver. Restoration of the ringing key releases the relays L and consequently W1, and removal of the receiver energizes X1, Y1 and so causes W1 to be shortcircuited. The reply signal is forwarded by the relays Y2-Y4 to S5(i) which lights the supervisory lamp SL. Control of numerical switches. The dial gives ground impulses at nsi to 15 which repeats them as interruptions of the circuit over which I4 is normally operated. V5, V4 remain operated throughout each digit and I4 repeats the first to the marking switch driving magnet DEW4. Since the wanted party is assumed to be in office U1, the terminals now marked by the marker are those with which the final selector LW4 is already in engagement. At the end of the digit a temporary circuit, interrupted by Q4 which falls sluggishly on the relapse of V4, is made over D4(i) and (ii), P40(i) and (ii) and the marker wiper ew1. P40 energizes U4 and locks over P40(iii). K4, which is operated on the first energization of DEW4, breaks the metallic circuit between the incoming and outgoing sides of the link and locks up on the consequent relapse of Y4. Y4 re-operates when P40 switches through, and K4 -is unlocked and falls back, but the incoming side of the link is now interrupted at contacts of U4. I3 at the previous office is now energized in series with X4 over a contact of I4 and the next digit is repeated by 14 and I3 and the switches at U3 are controlled in the same way as those at U4. The next digit is repeated to I2. V2, V20 remain energized throughout the digit which is repeated directly to the final selector driving magnet DLW2. K2 is energized by V20 and these relays cooperate at the end of the digit to make a temporary circuit in which D2, P20 pull up in series. P20 locks over P20(iii), holds D2 and energizes U2. The final selector LW1 is set in a similar manner, but in this case a circuit is completed over the calling loop when K1 operates for B1 which locks itself and releases X1. The relapse of Y1 when K1 operates is followed by that of Y2-Y4 and S5 and the supervisory lamp SL is extinguished. Busy test, ringing, reply signal. If the wanted party is idle, P10 pulls up in the test circuit and locks. The ringing relay W1 may be operated under control of the ringing key which causes the energization of the E relays, or automatically, under the control of a timing arrangement, shortly after P10 operates. When the called party replies, X1, Y1 pull up over his loop and the relays Y2-Y4, S5 pull up and light the lamp SL. If the wanted party is busy the failure of P10 to operate causes a busy signal to be given to the operator on the relapse of K1 over a circuit not shown. Release of setting path and release by subscribers. On the withdrawal of the plug, C50 releases H7 locally and I4 at U4, C40 falls and the switches go home. Similar operations take place in U3. In U2 the relapse of I2 energizes V2 which shunts out C2 to release C20, but at U1 B1, S1 are energized and so the V1 does not shunt out C1. The circuit is guarded from seizure by the connection of battery over Dr1 to the junction wire b1. This energizes Sp2 which, by removing a shunt from D2(ii) busies the junction to the switch LW2. When the subscribers hang up, B1, X1, Y1, S1, P10, C1, C10 fall back and the switches are restored. Calls to more remote offices. If a subscriber at U4 wishes to set up a call to U3 he gets into touch with the operator in the manner described above for a subscriber at U1. Since the call-finder at U4 is on a subscriber line instead of a junction, Q4 is not operated and the final selector remains stationary until the relapse of V4 when the marker has been set, whereupon it hunts for the marked position under control of P40. Completion of the call in U3 takes place in a manner analogous to that described for U1, except that the final selector is marker-controlled. Semi-automatic incoming calls. In establishing an incoming call, say to a subscriber U4, the operator does not at first operate the ringing key. Sleeve relay C50 causes the operation of I4, but since E4 is not energized the call finder does not move. The call is completed in a manner analogous to that previously described. If in a call to U3 the first U4/U3 junction is busy, P40 fails to operate when the final selector LW4 reaches position 3 and a further step is taken. If the other junction is idle P40 operates and the call proceeds. Automatic incoming calls; call storing. Seizure of the circuit Ue by a group selector causes the operation of C5, C60, H7. Relay A5 is disconnected and any existing outgoing call signal is thus postponed. The call is then established as previously described under control of the calling party's dial. If an outgoing call has energized A4, H5, H6 when the operator sets up a call to a subscriber in U4, H5, H6 are released, but A4 remains locked and the outgoing call is transferred to the other junction. If, however, the operator sets the final selector LW4 on to the calling junction, A4 is released by D4. A3, however, remains operated, and the outgoing call is transferred to the other U3/U4 junction. If the operator uses the calling U2/U3 junction for the incoming call A3 is released but A2 remains locked, and so on. The relay A in the originating office remains locked in any event and causes a calling signal to be given as soon as a chain of junctions to the main office is available. Modified call finder AS6, Fig. 12, for replacing AS4, Fig. 7. The call-initiating impulse from U3 energizes A6 which locks over A6(ii). If the link is idle, and has been so for a definite time, H8 is energized over a contact of thermal relay Th1 and makes circuits where