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 47
District No. 3 … from West; Offices As Changed to Meet Conditions Switching OfficeFromSouthOffices Fig. 30.—Trunking, inter-office, switching office moved to re-arrange districts. \\So three levels which were in service are trunked to third selectors in theoffices 21, 22 and 23 whose banks are multipled with the…
Telephone
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