The front of each plate states- One Bell System. It works.
100 Years of Telephony - 1876-1976.
The back of each plate states: The Centennial Plate Series
Commemorating 100 Years Of Communication Service To
Mankind made expressly for the Telephone Pioneers of
America by the Frankham Co. Canton, Ohio. Measures 10 3/4" inches in
diameter. NO box is included.
This is the "Undersea Cable" plate depicted in the image above.