UK national emergency alert test triggers millions of phone notifications; some users report delays
Government says 10-second siren was a routine test of a system for life‑threatening events as experts and campaigners warn of health and safety risks
Millions of mobile phones across the United Kingdom emitted a siren‑like sound and vibration at about 3 p.m. on Sunday as the government carried out a planned test of the national Emergency Alerts system, but some users reported the notification arrived late or not at all.
The test, the first of its kind since 2023, was scheduled for roughly 15:00 BST and sent to devices on 4G and 5G networks. Officials said the alert lasted about 10 seconds, was accompanied by a text stating it was a test, and was designed to assess the system’s performance ahead of potential use in life‑threatening situations such as severe flooding, fires or terrorist incidents.
Secretary of State for Work and Pensions Pat McFadden said ahead of the exercise that it was “only a test, just like the fire drills we all do in our schools and workplaces,” and that the government would work with mobile network operators afterwards to assess performance. Officials said the system does not require phone numbers or personal data to deliver alerts and that no device or location data would be collected or shared during the test.
Despite those assurances, charities and experts raised concerns in the run‑up to the exercise and reiterated them after the test. Medical and stress specialists warned the sudden loud sound could, in rare cases, trigger an acute stress response and a rapid rise in heart rate. Nicola Swanborough, head of external affairs at the Epilepsy Society, warned that loud noises may trigger seizures in some people with epilepsy. Campaigners also warned that the alerts could expose concealed phones used by victims of domestic abuse and urged those at risk to disable emergency alerts on hidden devices.
Officials said they had taken some measures to reduce disruption. They chose the 3 p.m. time to minimise impact on workplaces and schools and issued advance publicity across motorways, public transport hubs, museums, GP surgeries, concert venues and theatres. Still, sporting events and performances reported adjustments. The England third one‑day international cricket match against South Africa was scheduled to pause and the Super League derby between Hull KR and Hull FC had its kick‑off moved. The Globe Theatre said it would pause a performance of Twelfth Night to prevent disruption.
The alert system, which British officials say reaches about 95 percent of the population with 4G or 5G access, was launched in 2023 and has been used in real emergencies on several occasions. Government records show Emergency Alerts were sent to some areas earlier this year during Storm Éowyn, when about 4.5 million people in Scotland and Northern Ireland received a warning, and were used in Plymouth last year to help evacuate residents after the discovery of an unexploded Second World War bomb.
The government published guidance on how to opt out of the test for those who consider themselves at risk from the notification. On iPhones, users can go to Settings, select Notifications, and turn off Severe Alerts and Extreme Alerts. On many Android devices, users can search device settings for Emergency Alerts and switch off Severe and Extreme Alerts; the government advised contacting device manufacturers if alerts persist after opting out, because terminology and menu locations vary by make and software version.
Officials reiterated that alerts will only be used for rare, life‑threatening emergencies. They also advised drivers not to use hand‑held devices while driving and to stop in a safe place before reading an alert. The government said accessibility features would support people who are deaf, hard of hearing, blind or partially sighted by providing audio and vibration attention signals if such notifications are enabled on the device.
Similar cell broadcast systems are widely used internationally, officials noted. Japan and the United States operate national alert systems that combine unique sounds and messages; Japan’s J‑ALERT integrates satellite and cell‑broadcast technology for earthquakes, tsunamis, volcanic activity and missile threats. Other countries run regular tests at varying cadences—from monthly checks in some Nordic countries to annual exercises in parts of Europe.
After the test, the Cabinet Office and mobile network operators are expected to publish assessments of delivery performance, including any areas where alerts were delayed or failed to arrive. Ministers said the exercise was intended to ensure the system works effectively when needed to deliver life‑saving information, while acknowledging and seeking to mitigate the health and safety concerns raised by clinicians and advocacy groups.