Electronic devices sounded off across the United States Wednesday afternoon as the Federal Emergency Management agency conducted an emergency alert test.

The tone sounded at 11:18 a.m. PST. The subject read: "Presidential Alert" and text read: "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed."

It is the first test of the national wireless emergency system by FEMA. The message was broadcast on cell towers for 30 minutes. Some people got the alert multiple times. Others didn't get it at all.

FEMA estimated about 225 million electronic devices, or about 75% of all mobile phones in the country, would receive the alert. It hasn't said yet whether the test went well.

The system test is for a high-level "presidential" alert that would be used only in a nationwide emergency. The goal is to have phones get the alert at the same time.

FEMA says the test assessed the operational readiness of the infrastructure for distribution of a national message and determine whether technological improvements are needed.

Experts say every president since the 1950s has had this ability -- just not on cell phones.

This is the fourth EAS nationwide test and the first national WEA test. Previous EAS national tests were conducted in September 2011, 2016 and 2017 in collaboration with the FCC, broadcasters, and emergency management officials in recognition of FEMA’s National Preparedness Month.

If you didn't get an alert today, or want to give feedback on the test, you can email FEMA-National-Test@fema.dhs.gov.

Three New Yorkers had filed a federal lawsuit last week in an attempt to block the test. They argue it violates free speech and is an unconstitutional seizure of electronic devices.

(FEMA contributed to this report.)