1909 - Automatic Electric Company
Strowger 11 digit dial
Mint, original condition.
c.1908, extremely rare. This is the only one known to exist.
This is a very special and historically significant phone. The Strowger dial was the first automatic dial telephone but the early versions of the dial had two flaws. Calling impulses were irregular because the person dialing could not dial the number at exactly the same speed and there were also premature releases of the switches because the dial could go backward. The telephone shown here is the only known example of the Strowger dial after patented improvements began in 1909. This particular Strowger dial telephone has been provided with the common dial and also a supplemental or controlling dial, forcing the dial in a forward direction, but not backward. With this arrangement both dials will rotate forward and when a subscriber releases them, only the inner (or common) dial will then rotate back to the normal position. This prevents any forcing or accelerating of the backward rotation of the calling dial, inasmuch as the outside or supplementary dial is always positively locked against back rotation. An arrangement of this character insures the proper transmission of the electrical impulses for operating the switches at the exchange or central station.