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 166
ue. TRUNKING, ITS PHYSICAL ARRANGEMENTS AND VARIATIONS 149 The expansion of a system does not depend upon its original design, andit may grow as rapidly or as gradually as may be desired. A thousand-line exchange (Fig. 144) has originally not over ten groupsof 100 lines each. To expand it beyond… … Fig. 144.—Thousand lines being expanded. on the second selectors that they formerly occupied on the first selectors.The new numbers for these subscribers will be the old numbers with thefirst digit doubled. Thus, 245 will become 2245, etc. The remaininglevels of the newly installed second selectors…
Telephone
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