On Wednesday October 4th at 2:20 PM EDT, the Federal Emergency Management Agency (FEMA) will conduct a test of the Integrated Public Alert and Warning System (IPAWS)
To ensure you're aware, FEMA is scheduled to conduct a national-level Integrated Public Alert and Warning System (IPAWS) test on Wednesday, October 4th at 2:20 PM EDT. Test messages will be sent to TVs and radios through the Emergency Alert System (EAS) and cell phones through Wireless Emergency Alerts (WEA).
All major U.S. wireless providers participate in Wireless Emergency Alerts (WEA) and will transmit the national test to their subscribers. All connected and capable cell phones (with alert notification turned on) should receive the test. Phones should only receive the test once.
The backup testing date is October 11th. More info from FEMA can be found here.
Additionally, the required NOAA Weather Radio weekly test will proceed as normal around 11:00 AM EDT.