The Federal Emergency Management Agency will next month test a new “presidential alert” system that will allow the president to send a message to every phone in the US.

The alert is the first nationwide test of the presidential alert test, FEMA said in an advisory, which allows the president to address the nation in the event of a national emergency.

Using the Wireless Emergency Alert (WEA) system, anyone with cell service should receive the message to their phone.

“THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed,” the message will read.

Minutes later, the Emergency Alert System (EAS) will broadcast a similar test message over television, radio, and wireline video services.

The alert was due to be sent out on Thursday at 2:18pm ET, but will now run on October 3, FEMA said in a tweet.

Emergency alerts aren’t new and warning systems have long been used — and tested — in the US to alert citizens of local and state incidents, like AMBER alerts for missing children and severe weather events that may result in danger to or loss of life.

But presidential alerts have yet to be tested. Unlike other alerts, citizens will not be allowed to opt out of presidential alerts.

Allowing the president to send nationwide alerts was included in the passing of the WARN Act in 2006 under the Bush administration, creating a state-of-the-art emergency alert system that would replace an aging infrastructure. As alarming as these alerts can (and are designed to) be, the system aims to modernize the alerts system for a population increasingly moving away from televisions and towards mobile technology.

These presidential alerts are solely at the discretion of the president and can be sent for any reason, but experts have shown little concern that the system may be abused.

But the system isn’t perfect. Earlier this year, panic spread on Hawaii after an erroneous alert went out to residents warning of a “ballistic missile threat inbound.” The message said, “this is not a drill.” The false warning was amid the height of tensions between the US and North Korea, which at the time was regularly testing its ballistic missiles as part of its nuclear weapons program.

More than 100 carriers will participate in the test, FEMA said.

Update: with a new date, following bad weather on the US east coast.