This device, called a SECODER, mechanically decodes the pulse stream from the conventional telephone dial. This unit was originally used for selective calling in mobile radio applications for the railroad. I can't remember how it was that Rick happened to have one. website 
YOUTUBE xCc4F2ulBYc Uploaded on Oct 30, 2008
"AboutUs CTO, Ward Cunningham and his college roommate Rick Wartzok, had better than average audio/visual and beverage capability in their dorm room, at least for 1968. While happy to share with fellow residents, they then faced a dilemma. What about keys? They wanted some kind of combination lock that had a shared code that could be selectively enabled, and a longer, master code for private use. The solution was Dial-a-Door. Now its 2008, forty years later, Ward has located the mechanical technology that decoded the combination, restored it to working order, and prepared a display which he will present at the bi-weekly DorkbotPDX at the Lucky Lab in Northwest Portland." Courtesy of Mark Dilley.