The Civil Defense Warning Siren (CDWS) controller was a controller manufactured by Western Electric Co. for Bell or AT&T Telephone Co. This controller was a unique style consisting of a central console that looked like the dial to a desktop rotary phone, as well as a light up board that stated what signal the sirens were currently sounding. This controller, when used, sent a signal via. phone relay to receivers mounted to sirens. When a signal was received, sirens were activated. To activate sirens, a certain section had to be dialed twice within 5 seconds. The dial had 5 sections. 4 for siren signals (Test (1), Attack (3), and two instances of alert (2 and 4)), , one for cancel. In Bell literature, the controller was initially thought of during WWII, however the first know iteration of it is from 1950. The earliest known instance of this controller appearing anywhere was in a 1960 civil defense film that was shot in the Washington, DC metro. The controller did also have some screentime in 1978's Day of the Killer Tornadoes. It is currently not known when this controller was taken out of production, however a logical guess would be the late 1970s or early 1980s.
(PDF) Bell System publication from January 1968 pertaining to the CDWS. unknown. Retrieved March 6, 2018. </ref>