UK emergency alert test sounds on millions of phones amid health and privacy backlash

Millions of UK mobile phones connected to 4G and 5G networks vibrated and emitted a siren-like tone on Sunday at about 3 p.m. BST as the government carried out a nationwide test of the Emergency Alerts system — a measure ministers say is designed to deliver life-saving information during rare, serious incidents.

The test, the first of its kind since 2023, lasted roughly 10 seconds and also displayed a message on compatible devices indicating that the alert was only a test. Officials said the timing was chosen to minimise disruption, but users across Britain reported the notification arriving later than expected or not at all, and some sporting fixtures and cultural events adjusted their schedules to accommodate the alarm.

Secretary of State for Work and Pensions Pat McFadden, who had urged the public to remain calm, described the exercise as equivalent to routine safety drills. "The test takes just ten seconds, but it helps us keep the country safe 24 hours a day, 365 days a year," he said. The government has emphasised that the system will be used only in extreme circumstances such as severe flooding, major fires or terror attacks.

Critics and campaigners renewed warnings ahead of the test that the alarm could have unintended consequences. An expert in acute stress responses told reporters that the abrupt sound could trigger a fight-or-flight reaction and, in rare cases, provoke cardiac problems in susceptible people; the Epilepsy Society said seizures can be precipitated by loud, sudden noises and advised caution. Domestic-abuse charities also urged awareness that concealed phones used by people seeking help could be exposed by the alert and encouraged those at risk to disable the notifications on hidden devices.

The government said data about individuals, their devices or locations would not be collected or shared during the exercise and that mobile network operators do not need users' phone numbers to send the alert. Officials noted that about 87 million mobile phones are in use in the UK and that roughly 95% of the population has access to 4G or 5G service, the networks used to deliver Emergency Alerts.

Some events reported operational effects. The Globe Theatre announced it would pause a performance of Twelfth Night to avoid disruption, and organisers at sporting fixtures said they adjusted kick-off times and paused play in some instances. Emergency planners in the Cabinet Office Briefing Rooms (COBR) Unit said the timing of the test was selected to be the largest public-safety exercise of its kind without causing undue disruption.

The alert system has been used in several real incidents since its launch in 2023, officials said. Most recently, 4.5 million people in Scotland and Northern Ireland received an alert in January during Storm Éowyn, and in Plymouth the system helped evacuate more than 10,000 residents after an unexploded Second World War bomb was found.

The government reiterated that people concerned about receiving the test can opt out on many devices. On iPhones, users can go to Settings, open Notifications and turn off "severe alerts" and "extreme alerts." On Android devices, users can search Settings for "emergency alerts" and disable "severe" and "extreme" notifications; naming and placement of these options may vary by manufacturer and software version. The government website advises people to contact device manufacturers if alerts continue after opting out.

Officials highlighted that similar cell broadcast systems operate in other countries, including the United States, Japan and South Korea, where they are used routinely to notify the public about natural disasters, civil emergencies and other hazards. Ministers said the UK exercise is part of routine preparedness work and that they will review performance with network operators after the test. They also said they will continue engagement with charities and campaigners to address concerns, particularly those affecting vulnerable people.

The test was scheduled for around 15:00 BST on 7 September 2025 and was intended to confirm that the Emergency Alerts system works effectively across 4G and 5G networks. Officials reminded drivers it is illegal to use a hand-held device while driving and to pull over safely before reading any message, and noted that audio and vibration alerts can support accessibility settings for people who are deaf, hard of hearing, blind or partially sighted.