“The EAS [Emergency Alert System] is a national public warning
system that provides the President with the communications
capability to address the nation during a national emergency,”
The test message will have a header that reads “Presidential
Alert,” according to the agency. Users whose phones are on will
twice hear a tone and vibration and then see an English-only (for
now) message: “THIS IS A TEST of the National Wireless Emergency
Alert System. No action is needed.” […]
FEMA stated that the government cannot track end users’ location
through this alert system. The test is supposed to take place at
2:18 p.m. EDT on Sept. 20.
Under the Warning, Alert, and Response Network (WARN) Act of 2006,
cellphone users cannot opt out of the presidential alerts.
I’m sure Trump would never abuse this.