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 42
3rd. Thou. … Office- 45000-4800Q | Fig. 22.—One first-selector level for two offices r I Office -42 OOP- 43000 We may let two offices share one level of first selectors. (Fig. 22.)Assume a 100,000-line system. There are five digits in the call number.The illustration concerns the fourth level. Numbers in the…
Telephone
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