Presidential alert: Why did Trump just text me about a ‘test of the National Wireless Emergency Alert System’ and how does it work?

'THIS IS A TEST of the National Emergency Alert System,' the long message began

Donald Trump has texted everyone in the US the exact same message.

At 2.18pm eastern time, phones across the country woke up with a loud tone and an alert about a text message. "THIS IS A TEST of the National Wireless Emergency Alert System," the message began.

Almost every phone in the country received the message – making a sound when they got it, even if they were on mute, and with notifications even showing on smart watches – and it arrived only only once. It's possible some received it later, since it was broadcast for half an hour.

The message is exactly what it says: a test of a way for the president to send a message to everyone in the country. It would only ever be used in a national emergency, and has been developed in collaboration with the Federal Communications Commission.

There is no way of getting around the alerts. Phone companies have to build them into their devices and users cannot turn them off, unlike the similar alerts that are sent for missing children and natural disasters.

It is the first time that such a text message has been tested, though some users will be familiar with those similar alerts. The wireless emergency alert system sends out messages about hazardous weather like tornadoes and AMBER alerts about children who are missing to ensure that information is communicated as quickly as possible.

They began in 2012, and are run by carriers on behalf of their customers.

A similar message was sent on television broadcast and radio two minutes later. That has been tested for several years.

This is the full wording that people will hear:

THIS IS A TEST of the National Emergency Alert System. This system was developed by broadcast and cable operators in voluntary cooperation with the Federal Emergency Management Agency, the Federal Communications Commission, and local authorities to keep you informed in the event of an emergency. If this had been an actual emergency an official message would have followed the tone alert you heard at the start of this message. A similar wireless emergency alert test message has been sent to all cell phones nationwide. Some cell phones will receive the message; others will not. No action is required.

The alerts had been scheduled for a test on 20 September. But they were delayed until 3 October because FEMA, which facilitates them, was busy responding to Hurricane Florence.