There's a nationwide test scheduled for Wednesday at 11:20 a.m. Pacific Time (2:20 p.m. Eastern) of FEMA's Emergency Alert System, and it's being sent to all cellphones on all major carriers.

Don't get too excited if you hear it — or at least remember this warning when you do. This is, as they say, only a test.

FEMA's Wireless Emergency Alerts have to be tested every three years, and the last test was in 2021. The tests will be sent out between 11:20 a.m. and 11:50 a.m., but you should only receive it once — and it won't interrupt a call, if you're on one when it first comes through.

There will also be a one-minute test at that time on radio and television — you should know the spiel by now. "This is a nationwide test of the Emergency Alert System, issued by the Federal Emergency Management Agency, covering the United States from 14:20 to 14:50 hours ET. This is only a test."

FEMA has a fact sheet online about the Wireless Emergency Alert (WEA) testing.

"If you have a WEA-compatible mobile phone that is on, within range of an active cell tower, and on a network where WEA is supported, you should receive the national test," they say.

And, FYI, this isn't a test you can opt out of.

"Recent models of mobile phones may include a setting to opt-out of tests and alerts. None of those settings will affect the 2023 national test," FEMA says.

If there is some real national emergency or weather disaster tomorrow, the backup testing date is in a week, on October 11.