Mobile phones in the UK are about to ring out with another alarm as the Government tests its emergency alert system once again.
At 3pm on Sunday (September 7), the 'Armageddon alarm' will be sent to all 4G and 5G-enabled phones and tablets.
Devices will vibrate and emit a siren-like tone for 10 seconds, while a text box will appear giving more information.
The government says this latest round of coordinated phone buzzing is a crucial test of the UK Emergency Alert System.
However, it appears it is not compulsory.
A government webpage tells people how to opt out of emergency alerts - and it barely takes a minute.
Cabinet minister Pat McFadden, Chancellor of the Duchy of Lancaster, says: 'Emergency Alerts have the potential to save lives, allowing us to share essential information rapidly in emergency situations including extreme storms.
'Just like the fire alarm in your house, it's important we test the system so that we know it will work if we need it.'
This will be the first time that the Emergency Alert System has been tested in two years, following the system's launch in April 2023
Emergency alerts 'contain life-saving information and should be kept switched on for your own safety', the UK government webpage stresses.
However, it admits victims of domestic abuse with a concealed phone 'may find it appropriate to turn off alerts'.
It has therefore laid out the steps to opt out on an iPhone and Android - and they should work for everyone.
If on an iPhone, opt out by going to 'settings' and selecting the 'notifications' menu, then scroll to the bottom and turn off 'severe alerts and 'extreme alerts'.
If on an Android device, search your device settings for 'emergency alerts' and then turn off 'severe alerts' and 'extreme alerts'.
The government webpage says people should contact their device manufacturer for help if they are still getting alerts after opting out.
Also, depending on the manufacturer and software version of your phone, emergency alerts settings may be called different names.
These might include 'wireless emergency alerts' or 'emergency broadcasts'.
The emergency alert is used to warn if there is a danger to life nearby, in instances like extreme weather - although Sunday will only be a test
Emergency alerts 'contain life-saving information and should be kept switched on for your own safety', the UK government webpage stresses
Sunday will be the first time that the Emergency Alerts System has been tested in two years, following the system's launch in April 2023.
It was introduced to quickly inform the public of an impending threat such as severe flooding, wildfires, or extreme weather events.
When it was first tested, the emergency system sent a message to phones which read: 'Severe Alert. This is a test of Emergency Alerts, a new UK government service that will warn you if there's a life-threatening emergency nearby.
'In a real emergency, follow the instructions in the alert to keep yourself and others safe.
'Visit gov.uk/alerts for more information. This is a test. You do not need to take any action.'
Since its introduction, the Emergency Alerts System has been used in real life scenarios five times, primarily during major storms when there was a serious risk to life.
The largest ever use saw approximately 4.5 million people in Scotland and Northern Ireland receive an alert during Storm Éowyn in January 2025, after a red weather warning was issued.
The system has also been used in more localised incidents, such as when an unexploded World War II bomb was uncovered in Plymouth.
The alert system was used in Plymouth after an unexploded World War II bomb was uncovered and had to be removed
Similar systems are already used widely across a number of other countries, primarily for natural disaster preparation.
Japan has one of the world's most sophisticated systems, which combines satellite and cell broadcast technology.
This system forms part of a wider scheme called J-ALERT that informs the public in case of earthquakes, tsunamis, volcanic activity, or missile threats.
South Korea frequently uses its national cell broadcast system to alert citizens about issues ranging from weather alerts and civil emergencies to local missing persons cases.
The US has a similar system to the UK that utilises 'wireless emergency alerts' to send messages that look like texts with a unique sound and vibration pattern.
Everything you need to know about the Emergency Alerts System test on Sunday
What time will the test take place?
The test will take place at around 15:00 BST on 7th September 2025.
Why is the test taking place?
Regular testing ensures the system is functioning correctly, should it be needed in an emergency.
Who will receive the test alert?
Emergency Alerts work on all 4G and 5G phone networks in the UK. Your mobile phone or tablet does not have to be connected to mobile data or Wi-Fi to get alerts.
However, you will not receive alerts if your device is turned off; connected to a 2G or 3G network; Wi-Fi only; or not compatible.
What will the test look and sound like?
Devices will vibrate and make a loud siren sound for roughly 10 seconds. A test message will also appear on screens.
What will the test message say?
The government will publish the test message in due course. It will make clear the alert is only a test.
Do other countries run similar tests?
Lots of other countries operate similar emergency systems and run regular tests, including Japan and the USA.
Some countries test their systems monthly, such as Finland, while other countries test their systems annually, such as Germany.
What about my personal data?
Data about you, your device or location will not be collected or shared.
The emergency services and the UK government do not need your phone number to send you an alert.
What should drivers do?
It is illegal to use a hand-held device while driving. Find somewhere safe and legal to stop before reading the message.
What a victims of domestic abuse?
Emergency alerts potentially contain life-saving information and devices should be kept switched on for your own safety. However, there may be some scenarios where it is sensible to opt out of alerts, including victims of domestic abuse with a concealed phone. The government will continue ongoing engagement with domestic violence charities and campaigners in the run up to the test, to ensure people know how to switch off alerts on a concealed phone.
What about people who are deaf, hard of hearing, blind or partially sighted?
During the test, audio and vibration attention signals will let you know you have received an alert, if accessibility notifications have been enabled on your mobile phone or tablet.