The U.S. government has delayed its test of a modern text-based version of the emergency broadcast system, known as a presidential alert, from this Thursday to October. This comes after some people were vowing to turn their cellphones off in a sign of protest.

The bottom line: What would ordinarily be just a test of a modern age emergency warning has turned political, because this is the Trump administration and everything is political.

How it works: Americans have been getting various emergency messages sent to their phones since 2012, including weather warnings and Amber Alerts. The same system also allows the president to send alerts in the event of a nationwide emergency, though no such message has ever been issued.

While similar to text messages, the emergency alerts, including presidential alerts, are actually shorter (a maximum of 90 characters). They also come with a special alert tone designed to distinguish them from other messages.

The commercial mobile alert system, as the effort is known, is a public-private partnership involving the wireless industry, the FCC, FEMA and the National Oceanic and Atmospheric Administration.

What to expect: Phones that are on should get a message with a header that says "Presidential alert" followed by text that says "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.”

Why the test? The government wants to make sure that the system it has in place will actually work as intended. It has tested cellphone alerts before, but this is the first nationwide test for one part of the system.

Be prepared: The government has been running commercials preparing people for the test in a series of public service announcements. One interesting tidbit in the ad I saw was that the alert came in on a Windows Phone, rather than the far more widely used Android or iOS — perhaps the government didn't want to take sides on such a divisive issue.

No stopping it: Consumers can choose to opt out of the Amber alerts and weather warnings, but not presidential alerts. And that's where the protest comes in, with a number of people tweeting that they plan to turn off their devices Thursday and encouraging others to do the same. There's even a hashtag, #godark920.

Trump fears: It's entirely up to the president what to say and when, so there is some fear — stoked by the publicity around Thursday's test — that the president could use it to send partisan messages.

History lesson: There have been issues with past tests, most notably one in Hawaii back in January that briefly terrified residents in the state into thinking they were on the receiving end of a ballistic missile attack.

Editor's note: This has been updated to reflect the delay.