Strowger two-motion selector with vertically mounted relays, less switching banks, made by the Automatic Telephone Manufacturing Company, Liverpool, England, 1903-1920

Strowger two-motion selector with vertically mounted relays, less switching banks, made by the Automatic Telephone Manufacturing Company, Liverpool, 1903-1920.

The earliest type of automatic exchange equipment to gain widespread use was the Strowger or step-by-step design. This Strowger two-motion selector is of the same type as those installed in Epsom in 1912 as part of Britain's first public automatic telephone exchange.