An oldie, but a goodie, February 20, 1971, WOWO gets an EAN via AP teletype and follows the procedure:
Back in the days of EBS, there were weekly closed-circuit tests via AP and UPI teletype. In the event of a real Emergency Action Notification (EAN) there was a red envelope that contained a set of code words for each month. The test code words were on the outside of the envelope. If an EAN was received, the envelope would be torn open and the actual code words would be matched against the code words in the message. If it were authenticated, then the station would do just what WOWO did right then, send the two-tone EBS alert for 25 seconds and break into programming.
It is amazing that this did not happen more often, especially on a Saturday morning with a sleepy Airman in Colorado pulling the wrong message tape off the rack at the message center responsible for the whole system.
It happened more recently when an EAS message was sent to evacuate the entire state of Connecticut. An EAN was sent in Chicago warning of a national attack when state officials were testing their new system. I am sure that others have been sent as well.
I suppose the emergency notification has always left something to be desired.