A SIREN will sound on millions of phones across the UK for the Emergency Alert system test in September 2025.
But fear not, it is just a and no cause for alarm — here’s everything you need to know.
A National Emergency Alert System test was also carried out on April 23, 2023
During the , phones will vibrate and emit a siren-like tone for up to 10 seconds.
A message will also appear on screens, making clear it is only a drill.
Chancellor of the Duchy of Lancaster, , said: “It will be one of the UK’s largest public safety exercises in history.”
“It is a vital tool for keeping the nation safe when lives are on the line — and every minute matters.”
The Government has used the system to issue real warnings five times in the past.
In January 2025, , the system warned people in Scotland and about severe weather.
Approximately 3.5 million people across and south-west in December 2024.
In February 2024, a 500kg unexploded Second World War bomb found in a back garden triggered a warning to some 50,000 phones.
Messages can be targeted to relatively small areas to pinpoint those at risk.
Some 15,000 phones were alerted during flooding in in May 2024, and 10,000 received a warning during flooding in Leicestershire in January this year.
When is the Emergency Alert test?
The next on mobile phones will take place on Sunday, September 7, 2025 at 3pm.
The Government will to ensure the system works properly, and also familiarise the public with these emergency notifications.
The alert will cause mobile phones and tablets to emit a loud siren and vibrate for about 10 seconds — this will happen even if your device is set to silent mode.
The message will make clear that it is a test and no action is necessary.
It is a vital tool for keeping the nation safe when lives are on the line — and every minute matters
Pat McFadden
Who will receive the Emergency Alert?
Most people with compatible devices will receive the alert, including:
- Anyone with a compatible mobile phone or tablet using a UK 4G or 5G network.
- Devices that are switched on and not in airplane mode at the test time.
- Devices do not need mobile data or Wi-Fi enabled to receive alerts.
- The system is designed to be accessible, including vibration and audio cues for people with disabilities.
All major UK mobile networks are participating, aiming to reach nearly 95 per cent of mobile users in the UK.
The message will appear based on the device’s location, not the registered user’s address.
Who won’t get the Emergency Alert?
Some phones will not sound the siren or vibrate for reasons including device/network limitations, opting out, or device status at the time of the test.
The following people and devices will not get the test alert:
- Phones and tablets using only 2G or 3G networks, or devices that are Wi-Fi only and not SIM-enabled.
- Devices that are switched off or in airplane mode at the test time.
- Older handsets that do not support the Emergency Alert feature.
- Those who have manually opted out of emergency alerts via their device settings.
- People in places with poor mobile network coverage.
- In previous tests, some users didn’t receive alerts due to technical glitches.
If someone cannot receive alerts, emergency services will continue to deliver warnings through other means, such as TV and radio.
