There will also be a television broadcast and radio alert at 2:20 p.m. EDT, which has been tested for several years.
The Federal Emergency Management Agency (FEMA) and Federal Communications Commission originally scheduled the test for September, but they pushed it back due to Hurricane Florence. "No action is needed", the full text will read.
The alert will not come across a phone if it is powered off. Cellphones must be equipped to support the Wireless Emergency Alert System to comply.
Americans can opt out of those, but the new national alert system does not allow for that.
The test is made available to EAS participants, officials said. The alert won't have any substantial content - it's just a system test - but this sets a whole new precedent for how Americans are informed. With other messages like AMBER alerts and flood warnings that automatically pop up on people's phones, many carriers let you go into your phone's settings to shut them off. It wasn't until Wednesday that it got its first test.
Tiffany Trump is the president's daughter whom he had with his second wife, actress Marla Maples.
The Emergency Alert System message will be longer. TV and radio alerts have been tested before. But the best-case scenario is that no emergency ever happens that's serious enough to warrant a nationwide phone alert.
FEMA says this is the first national test to examine whether a direct message from the President is reaching all intended users.
"Officials - including [President] Trump - are free to define "act of terrorism" and "threat to public safety" as they see fit, potentially broadcasting arbitrary, biased, irrational and/or content-based messages to hundreds of millions of people", the legal action claimed.
The FCC said it does not collect data based on the test, though it will ask cell service providers for feedback about how the test went.
Jeh Johnson, Homeland Security chief, told CBS This Morning that the alert is only used for "true emergencies when we need to get the public's attention". Shortly after the alert was sent, FEMA shared a poll on Twitter asking if people received it.
And students said when to use the system for real is a question.
If you're in range, though, you're getting the alert whether you like it or not.