Fuente: Wipo "digitalization" 692,999. Automatic exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. Feb. 1, 1950 [Feb. 12, 1949], No. 2630/50. Class 40 (iv). An automatic exchange comprises a plurality of register senders each including a plurality of digit registers and a control switch, the exchange also comprising a translator with a plurality of translating devices each individual to a called exchange and means for associating one of the register senders and its control switch with the translator. Figs. 4-31 are arranged to form one circuit as shown in Fig. 32. Selection of idle primary selector and idle director. Closing the loop at substation 401 employs distributer 442, rotary distributer 441, and idle line finder 440 in known manner to connect the subscriber's line conductors 402, 403 to conductors C444, C445 of the associated primary selector 500, line relay R530 operating to energize hold relay R540, which maintains the line finder 440 and cut-off relay R410 and at contacts 546 initiates operation of director hunter, 450, rotary magnet M451 operating intermittently to advance the wipers 453-460 until absence of ground on the contact associated with wiper 460 indicates an idle director, when director test relay R510 operates, its high resistance preventing operation of M451. Relays R530, R540, R550 then relapse. Operation of director hunter and primary selector if all associated directors are busy. If a director is available, relay R601 grounds contacts 23, 24, 25 to enable wiper 460 to advance, if necessary, into engagement with contact 1 again. When a director is in use, its busy relay R610 grounds conductor C475 and energizes director busy relay R606, When all associated directors are busy, relay R601 releases to remove ground from conductors C465-C467, whereby the wipers can stop on contacts 23-25. If, now, the wipers engage contacts 23, they seize hold and busy tone circuit 582 and director test relay R510 operates to halt the wipers and mark contact 23 busy. Relays R580, R585, R590 energize to actuate a busy meter (not shown) and transmit busy tone over conductor C595 to the calling subscriber. If other calls are made while the first hold and busy tone circuit is in use, the director hunter advances its wipers to position 24 or 25 to operate a second or third hold and busy tone circuit 583 or 584. Circuit 582, 583 or 584 is released when the related subscriber hangs up. Seizure of an idle director. When the director hunter 450 seizes an idle director, wipers 456, 457 extend the calling loop over conductors C470, C471 to the code switch 1100 over both windings of party line relay R 1130 and the upper winding of line relay R1140, the latter pulling up but R1130, being differentially wound, not operating. R1140 operates hold relay R1150 which energizes seizure relay R750 in the controller 600 and connects impulse conductor C1135 to wiper 1192 to apply twelve impulses per minute to timer 1190. Seizure relay R750 (1) applies ground to conductors extending to coder 1800, call register 1500 and call recorder 2000, (2) locks director test relay R510 and operates hold relay R820, (3) operates director busy relay R610 and biases delay send relay R910, (4) starts pulse generator 700, which applies pulses to pulse relay R880 at a rate of ten pulses a second. Class test. Hold relay R820 energizes class test relay R720. If ground from terminal 425 is jumpered to terminal 428 in the line circuit 405, relay R670 energizes to show that the calling line requires class 2 service. R720 also energizes control relay R730 slowly to restore R720. If resistance battery from terminal 426 is jumpered to terminal 428, relay R710 pulls up to show that the calling line requires class 3 service. If neither R670 nor R710 energizes, the line requires class 1 service. Restoration of R720 restores R730 slowly and operates R760 to light the appropriate class indication lamp 676-678 and extend dial tone to the calling line. Dialling called number. (1) First digit. The subs