GB654096A - Telephone systems - Google Patents

Abstract

654,096. Automatic exchange systems. WESTERN ELECTRIC CO., Inc. Feb. 27, 1948, No. 6068. Convention date, Oct. 31, 1940. Drawings to Specification. [Class 40 (iv)] In a large cross-bar toll office, the same senders are used for dealing with calls having 3, 4 and 5-digit routing codes, and the appropriate. digits are transferred from the sender registers to the marker as soon as the code is complete to control selection of an outgoing trunk to a distant toll office, to a terminating office or to a delayed outward toll switchboard. An incoming trunk is connected in known manner to a sender which receives a preliminary signal from the incoming trunk circuit to operate one or other of two class relays to indicate whether the call is to go to a further toll office or is to be completed in the toll area. Each code digit is received as a pulse on either or both wires of the incoming trunk which are connected at this time to two sets of three relays, one being marginal and one polarized, and the digits are transferred in succession to a series of relay registers. After the third digit of a 3-digit code has been registered, the A, B and C registers of the sender transfer their record to the marker, which controls a first group of route relays. A 4-digit code, which indicates a call to a further toll office, has the first digit 0, and this energizes a 4-digit relay which, in conjunction with the class relay, operates a relay in the marker to switch in a second group of route relays and causes the transfer of the record from the B, C and D registers of the sender to the marker when the code is complete. Similarly, a 5-digit code, which indicates a call terminating in the area, has the initial digits 11, and a 5-digit relay in conjunction with the class relay effects the switching in of a third group of route relays and the transfer from the C, D and E registers of the sender. Subsequent digits are recorded on later registers of the sender and are transferred to an outgoing sender and re-transmitted over the out-going trunk as soon as a terminating pulse is received, the latter being acknowledged by a backward signal over the incoming trunk. Specifications 642,455 and 653,002 are referred to.