Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 164
parated andnew trunks run to new second selectors for one district (4). (See lowerpart of Fig. 142.) This step might be made necessary by an unex-pected increase in the traffic, even if the number of offices did notincrease to the overlapping point. Not all offices and districts need to trunk into… … l-S
Telephone
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