What's actually going to happen when emergency alert blasts through everyone's phones

Here is what you can expect to happen when the UK tests its national emergency alert system.

Tomorrow (7 September) will see phones across the UK emit an emergency siren as the nation conducts its second testing of an alert system designed to give warning and advice in the event of a life threatening emergency.

The system was first tested back in April 2023 to mixed success, with Brits on Three (this writer included) unable to receive the alert due to issues on the network, which is certainly reassuring to know should imminent disaster strike the country.

The government later confirmed they were working to resolve the issues, which means that all of us should receive tomorrow's alert.

So, here is everything you can expect to happen.

It might be a good idea to turn your phone off if you're heading to the cinema tomorrow afternoon (Getty Stock Images)

What will happen to your phone when during the national emergency alert system test?

According to the government website, the alert is set to go off at 3pm on Sunday, 7 September. The alert will only be available on 4G and 5G devices.

When the clock strikes three o'clock, your phone will vibrate and make a loud siren-like sound (even if its on silent) for about 10 seconds as the alert is read aloud.

The alert will also include a link to the government website for more information.

In this circumstance, the alert will clearly state that it's a test, however, real alerts will be sent for incidents such as wildfires, flooding and extreme storms.

The alert has been used several times since the first test, notably in areas hit heavily by Storm Darragh in December 2024, and an unexploded WW2 bomb uncovered in Plymouth.

Users who are driving at the time of the alert sounding are advised not to respond to the alarm until they've been able to pull over in a safe space.

The alert can be switched off if needed (Getty Stock Images)

Can you opt out of receiving emergency alerts?

It is possible to alter the settings on your phone to switch off the emergency alerts, but the intrusive government recommends that everyone keep them switched on as they could potentially provide life-saving information.

For users where it would not be safe to have an alert on their phones, such as domestic violence victims who own a secret mobile. This involves going into the settings on your device and switching off 'severe' and 'extreme' alerts.

Complete guidance on how to complete this on both iPhone and Android phones is available here on the government website.

It's also possible to opt out of receiving alert tests on your phone, which you can find out how to do here.