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 165
special second selectors havetheir second levels multipled onto the regular trunks leading to thecentral office. In the upper part, if any office (No. 5) calls 12, thecall goes to an incoming second selector in office No. 3. Calling Olifts the incoming second selector to the tenth level, leading to… … l^ \sMs =^frnplaJc 1 rzr~—In formati T ■ Fig. 143.—Trunking, recording toll and miscellaneous service. Calling the same number from any office (No. 7) in the lower partroutes the call over a regular trunk to office No. 2, where similar condi-tions prevail. Complaint is called by 1303. Levels 2 and…
Telephone
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