FEMA and FCC will conduct a national test of the Wireless Emergency Alert and the Emergency Alert System this fall. Cell phones, wireless devices, TVs and radios across the country will be sent a test alert around 11:20 am PT (2:20 pm ET) on October 4.

More info: https://www.fema.gov/press-release/20230803/fema-and-fcc-plan-nationwide-emergency-alert-test-oct-4-2023