Patent GB-191321735-A (GB)
Title: Switching System for Handling Traffic in One Direction only between Two Trunk Exchanges, in each of which the connection of the Concerned Subscriber Lines with the Junction Lines is Obtained by Means of an Order Wire Service.
Inventor: ARNTZENIUS CAROLUS ROBERT HENDRIK
IPC: H04M5/08
Filed: 1913-09-26
Granted: 1914-09-03
Abstract: 21,735. Arntzenius, C. R. H. Sept. 26,1912, [Convention date]. Exchange systems.-In making a trunk call to a distant town, the trunk line that is taken into use is automatically connected at the distant end to the order wire of an operator by whom the trunk is connected to the wanted line. The connexion is supervised by the operator at the calling trunk exchange. The invention enables the services of the customary operator at the distant trunking- exchange to be dispensed with. In the system shown in Figs. 3, 1, 2, and 4, which should be assembled side by side in the order named, the main trunking-exchanges are shown at I, Fig. 1, and II, Fig. 2, subordinate local exchanges being indicated at Io, Fig. 3, and II0, Fig. 4. The interexchange trunks I1, I2, I3 deal only with the traffic in the direction from I to II. The order wires of the second trunking-exchange II and its local exchanges are represented at D1, D2, D3 These order wires can be connected with the incoming trunks by relays b1, b2, &c., the order wire D1 with the trunk I1, D2 with I2, and so on. In the system illustrated, it has been assumed that there is only a single local exchange H0 connected to the second trunking-exchange II. In the more general case in which there are several local exchanges II<0>, each of the trunks I1, I2, &c would be provided with polarized relays or step by-step switches for connecting it with a junction line to the wanted local exchange. Connecting-operations. In response to a call for a trunk connexion by a subscriber 200, Fig. 3, at the local exchange I0, the local operator inserts the plug stI2 of a junction line L, (allotted over an order wire by an operator at the first trunking- exchange I, Fig. 1) in the calling-subscriber's jack. The operator at the trunk exchange connects the junction line L1 by a jack st2 to a trunk line I2 and throws a key s2. This energizes a relay a2, Fig. 2, individual to the trunk line I2 at the distant trunk exchange II, and if the order wire D2 allotted to the trunk I2 is disengaged, a relay b2 is energized and connects I2 to D2. If the order wire D2 is already engaged, the relay b2 fails to energize (being parallel with a relay B2 or C2 belonging to the operator Ft1 or Ft2 who is using the line D2), and the operator at the calling trunk exchange hears a buzzer signal from the circuit 17, 22 until the order wire D2 is clear. (In the same way if an operator Ft1 at the called trunk exchange presses a key 2 with the object of taking into use the order wire Dz, and if the order wire D2 is already in use either by a second operator Ft2 at the exchange II or by an operator at the exchange I, then the operator Ft1 hears a buzzer signal from the circuit 80, 83 and her listening-circuit H1 fails to get connected to the order wire D2, since the relay B2 cannot energize in parallel with the relay C2 or b2.) The operator at the exchange I having got possession of the order wire D2, communicates with the operator at the distant local exchange II0, who completes the connexion to the subscriber 400 by means of the plug stII2. Supervisory signals. When the plug stII2 is inserted, a relay i2 is energized in series with a relay k and energizes a relay c2, Fig. 2, which de-energizes the relays a2, b2 and energizes a relay d2 in series with a relay j2, Fig. 1, (the key S2 having been thrown back). The relay d2 cuts out the relay c2, which de-energizes the relay f2 (the holding- winding of this relay being at this time open at a contact, not shown, of the listening-key of the operator at the exchange 1), but the relay d2 itself remains locked over its second winding e2. When the subscriber 400 replies to the call, the retay i2 is short-circuited by the contact of the line-relay l, n and de-energizes the relay d2, e2, whereby the relay c2 is again connected to the circuit 36. When the subscriber 400 hangs up his receiver, the re-energization of the relay i2 energizes the relay c2, which energizes the relays d2, f2, and the relay f2 then locks itself up (the listening-key being thrown back) and lights the lamp li. As regards the calling subscriber, when he hangs up his receiver, the de-energization of the line relay r, q removes a short circuit from the relay O2, which energizes a relay g2, Fig. 1, lighting the lamp lc. Recording duration of conversition. At the commencement of a conversation, the operator at the calling trunk exchange I inserts a ticket in a shoot 60 and presses a key 63 to start clock-work 59. When both subscribers have hung up their receivers, the relays f2, g2 are both energized, and a circuit is closed for a magnet h<2> which operates a time stamp 62 and returns the clock work 59 to normal.