Fuente: Wipo "digitalization" 749,171. Automatic exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. Sept. 7, 1953 [Sept. 11, 1952], No. 24701/53. Class 40 (4). Metering apparatus at a central exchange records calling and called numbers in connections from the central to a remote exchange and also in the reverse direction. General arrangement, Fig. 15. In a call from a subscriber at central exchange B to a subscriber at the remote exchange C, the line circuit 120, distributer 123 and finder 121 operate in known manner. The subscriber then dials the necessary digits, say 90-6-521. The first digit selects an idle ticketer 700 and the second digit causes a detector 1900 to detect the calling line and the calling party so as to register the directory number of the calling subscriber in the ticketer 700. The third digit 6 is repeated by the ticketer to a trunk selector 801 which seizes an idle trunk circuit extending to a ticket repeater 900 in the wanted remote exchange C. The remaining digits complete the connection to the called subscriber. When the called subscriber answers the ticketer 700 starts timing the call and at the end of conversation the ticketer is associated with a tabulator to record the metering information. In a call in the reverse direction the local connector 1319 returns dialling tone. The subscriber at the remote exchange C now dials digits, say 90-521-4-4574. The first digit 9 causes the local connector 1319 to seize an idle ticket repeater 900 and the digit 0 causes the ticket repeater 900 to seize a trunk circuit 810 in the central exchange B so as to seize an idle ticketer 700. The identity of the calling party on a party line is registered at this time in the ticket repeater 900. The subscriber then dials his own directory number 521 and these digits are registered in the repeater 900 and in the ticketer 700. A verifier 1301 is then associated with the repeater 900 and if the calling number is found correct the verifier permits the repeater 900 to transmit subsequent digits to the ticketer 700 to complete the call. The information stored in the ticketer 700 is then transferred to the tabulator 745. Local calls are not recorded. Detailed description. Party line signalling devices. The dialling devices are of known type, stations on a party line having cam springs 111a-115a, Fig. 1, for sending a fixed number of station identifying ground impulses between certain loop impulses (Figs. 16, 17, not shown). Call from central exchange B to remote exchange C. In response to the closing of the loop the line is extended in the manner described in Specification 368,716 to the first selector 122 which returns dialling tone. In the example the subscriber now dials 90-6- 253. The first digit operates the first selector to seize an idle ticketer 700 by energizing seize relay R650, which operates line cut-in relay R450 to extend the line conductors through the left-hand windings of repeating coil 490 and a loop including local line relay R430 and polarized party line relay R420, only the former operating at this time. R430 operates control relay R50 which busies the ticketer and operates slave relay R480 to energize control relay R610. R610 energizes the lower polarizing winding of answer relay R270 which does not operate yet. Local line relay R430 operates pulse control relay R485 at the first pulse of the next digit 0 so that the digit is repeated to magnet M663 of the 0 register 660. In the interdigital pause R485 falls back and, according to whether 0 has or has not been registered in register 660, operates R640 or R470. In the latter case R470 breaks the circuit to pulse control relay R485, to prevent its response to further digits, and returns busy tone to the calling line. On the other hand correct registration of digit 0 causes R640 to prepare a circuit for transmitting subsequent digits to wiper 503 of the receive sequence switch 501 and operates detector start relay R220 to cause detector 1900 to register the calling number in the code