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There are two specific important individuals from Bell Telephone Laboratories who were very much involved in the continuing development of new and improved innovations for the #4-type XB Toll machine: Amos E.Joel, Bell Labs (1941-84), retired; and the recently deceased Robert J. In the charts/lists below: - the first column is the date of installation - - the second column is the CLLI (Common Language Location Identifier) of the switch.
The Bell System started introducing them in the 1940's to prepare for the semi-automated "Nationwide Operator Toll Dialing" introduced in the late 1940s, and for ultimate (fully-automated) customer-dialed 'DDD' (Direct Distance Dialing) introduced throughout the 1950's and 60's.WECO manufactured and installed them for service without any 'Card-Translator' Boxes.Actually, the Card Translator hadn't even been invented/developed at the time (1943).[NOTE: CLLI was developed by Bell Labs in the late 1960s and began to be used by AT&T Long Lines and the Operating Companies through the 1970s.With divestiture, management of the CLLI code assignments went with Bellcore (now Telcordia) Language Standards; ALSO, it _IS_POSSIBLE_ that a CLLI code used at one time for a switch that has been retired _COULD_ be re-used for a new switch] - the third column is the "rank" or "classification" of the switch within the DDD network hierarchy, _AS_OF_ the 1976 timeframe.