Expect your mobile to go off at 3pm this Sunday – here's why and what it'll sound like

Public emergency alerts, which use the 4G and 5G mobile networks, enable urgent messages to be broadcast to a defined area when there is an imminent risk to life, such as wildfires or severe flooding.

Since the alerts were first tested in April 2023, they've been deployed around the UK several times – for example, to warn three million people across Wales and south‑west England about dangerous conditions during Storm Darragh in December 2024.

This weekend's test is taking place to ensure the system is "functioning correctly" when it's really needed, the Government said.

What you'll hear when the alert happens

Depending on the device you have and its settings, your mobile or tablet may do one or more of the following:

• Make a loud siren-like sound, even if it's set on silent.

• Read out the alert.

• Vibrate.

The sound and vibration will last for about 10 seconds.

The video below gives you an idea of how the alerts will appear and sound (heads-up – it's LOUD):

Who will – and won't – get the test alert on Sunday 7 September

The alerts are sent by mobile phone masts that broadcast them to compatible devices in the surrounding area. It means millions of mobile devices connected to any of the UK's 4G or 5G networks will get the test alert – but not all.

You WON'T get the alert if your device is:

• Only connected to a 2G or 3G network (not 4G or 5G) – if you have an older device, see our 3G switch off guide for more info and help with this.

• Wi-Fi only (in other words, if it can't connect to mobile networks).

• Running an old version of iOS (from before around May 2021) or an old version of Android (from before around September 2020) – see which versions are supported and how to check yours.

• Turned off.

• Overseas.

If your device is in airplane mode, this should block the alert – but the Government told us it couldn't say for sure because settings vary from device to device.

The Government doesn't collect or use your phone number, location or any other personal details to send emergency alerts, and you don't need to download an app or sign up to receive them.

If you're driving, DON'T pick up the phone

It's illegal to hold and use a phone, sat nav, tablet, or any device that can send or receive data, while driving or riding a motorcycle.

When the alert goes off, don't pick up your phone if you're driving, as you could endanger yourself or any passengers, risk getting six penalty points and a £200 fine. The alert should stop by itself within a few seconds.

Charities have warned anyone living with domestic abuse to opt out of the alerts on any hidden devices

The domestic abuse charity Refuge has warned that, because the alerts will sound even if a phone is in silent mode, the test could alert an abuser to a concealed device. Other charities and organisations, including Solace, Women's Aid and local police forces, have shared similar warnings.

If you're concerned about this, you can opt out of emergency alerts in your phone or tablet's settings before the test at 3pm on Sunday 7 September. While you could simply switch the device off before the test, this won't prevent any future alerts from ringing – which could happen at any time given the alerts are now being deployed by the Government in real emergencies.

How to opt out of emergency alerts

If you'd prefer not to get the alerts, you can disable them in the settings on your device – though the Government does advise that you should keep them switched on for your own safety.

To opt out on iPhone:

1. Go to your settings and select the ‘notifications’ menu.
2. Scroll to the bottom.
3. Turn off 'severe alerts' and 'extreme alerts'.

To opt out on Android:

1. Search your settings for 'emergency alerts'.
2. Turn off 'severe alerts' and 'extreme alerts'.

Following the steps above should prevent the test alert from going off.