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 177
ach telephone connected to a cordless private branchswitchboard of this type may be equipped with an automatic callingdevice so that it will only be necessary, when an outgoing call is to bemade, for the operator to throw the keys required to switch the line of theparty who desires to make the call… … Fig. 157.—Private branch exchange switchboard. Fourth Class—Manually Operated Private Branch Exchange Switch-boards Using Cords and Plugs.—A reproduction of a photograph of asingle position switchboard of this type with a capacity of about 60lines is given in Fig. 157. This type of board is…
Telephone
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