On Thursday, FEMA will conduct a test of IPAWS: Integrated Public Alert and Warning System. It will send a message to all the phones in the US to test the infrastructure of the warning system. The test will happen around 2:18 PM ET and will last a half hour.
Rich says it's a big deal that the federal government will take command of every cell phone tower in the country in order to reach everyone at once with a test emergency text message. Rich also says that while there is an opt out provision for some emergency alerts, this isn't one of them. You cannot disable it.
Rich also says scammers could try and use the test to get you to do something. The official directive will state "NO ACTION IS NEEDED". So don't fall for any attempts to get you to log into or download something for the test. It's not needed.