. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . mmatically in Fig. 311. DEVELOPMENT STUDIES 413 Trunks for Reverting Sub-office Calls.—Since, as stated, a sub-officeline is instantly connected to a trunk to main office as soon as a calling;subscriber lifts his receiver from his switch hook (or makes the first turnof his dial if a three-wire system is used), it is evident that even if heshould wish to call another subscriber connected to his own office that theconnection will pass through the main office and will then be extendedback to the sub-office,
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . mmatically in Fig. 311. DEVELOPMENT STUDIES 413 Trunks for Reverting Sub-office Calls.—Since, as stated, a sub-officeline is instantly connected to a trunk to main office as soon as a calling;subscriber lifts his receiver from his switch hook (or makes the first turnof his dial if a three-wire system is used), it is evident that even if heshould wish to call another subscriber connected to his own office that theconnection will pass through the main office and will then be extendedback to the sub-office, in which the call originated, when the connectorswitch trunk is occupied. Therefore, as indicated in Fig. 312, such aconnection occupies two trunks between the sub-office and its main office. Where conditions warrant the use of somewhat more complicatedand expensive sub-office apparatus, equipment may be installed at asub-office which will avoid the necessity of using any trunk betweena sub-office and its main office during a local conversation. When Called Telephone ConnectorSwitch. Line SwitchDISTRICT STA.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
