UK to run nationwide emergency alert test on mobile phones Sunday
Compatible 4G and 5G smartphones will sound a 10-second siren at 3 p.m. BST as the government checks a system designed for imminent danger
The UK government will carry out a nationwide test of its emergency alert system on Sunday, 7 September, with compatible mobile phones set to emit a siren-like sound and display a test message at 3 p.m. BST.
The alert, intended for situations that pose an imminent danger to life such as extreme weather or terrorist incidents, will sound for 10 seconds and will do so even if phones are set to silent. The message will be pushed to smartphones operating on the country's 4G and 5G networks and will appear on devices whether or not they are connected to mobile data or wi-fi.
The government says there are about 87 million mobile phones in the UK and that roughly 95% of the population can access 4G or 5G. Older handsets and devices connected to 2G or 3G networks will not receive the test, nor will phones that are switched off or in airplane mode.
This is the second nationwide test of the system. A previous test in April 2023 exposed technical problems, with some users reporting they received multiple messages while others received none, and some devices alerted a minute earlier or later than planned. The current test is designed to confirm the system operates reliably when it is needed.
Pat McFadden, the work and pensions secretary who until a recent government reshuffle served as a senior Cabinet Office minister, said the exercise was aimed at ensuring the system "works well when we need it most." He urged the public to "keep their cool" when phones across the UK sound the alert and to remember that it is a test, likening it to routine fire drills in schools and workplaces.
The government has urged people to enable their devices to receive emergency alerts, saying that the notifications are an important public safety tool. Officials have said the test will explain that it is only a trial and will provide reassurance that the system can notify people quickly in life-threatening situations.
Officials have not indicated that every individual can be prevented from receiving the alerts through an official national opt-out, and have stressed the importance of broad participation to validate the system's reach and performance. Guidance on device settings for receiving or silencing alerts varies by manufacturer and operating system, and users seeking to change how their handset behaves during alerts should consult their device's support information.
The emergency alert system uses a cell broadcast method to send messages to devices in targeted geographic areas, allowing authorities to warn people in specific locations about immediate dangers. Tests are intended to assess technical delivery, timing and the clarity of messages so that, in a genuine emergency, authorities can communicate rapidly and effectively to protect lives.
The government has asked for patience from the public during the test and reiterated that no action is required when the test message appears other than to note that it is a drill. Authorities will review the results and any technical issues reported during the test to refine the system ahead of any future live use.