The UK government will carry out a nationwide test of its Emergency Alerts system at about 3 p.m. BST on Sunday, Sept. 7, 2025, during which millions of 4G- and 5G-enabled phones and tablets will vibrate, emit a siren-like tone for roughly 10 seconds and display a message stating the alert is a test.
Ministers urged the public to remain calm and treat the exercise as a routine safety check. Secretary of State for Work and Pensions Pat McFadden said the drill is intended to ensure the system works when needed and compared it to standard fire drills carried out in schools and workplaces.
The Government said the test will be the largest public-safety exercise of its kind and is designed to deliver life-saving information in extreme, life-threatening incidents such as major flooding, large fires or terror attacks. Emergency Alerts operate across all 4G and 5G mobile networks and do not require a device to be connected to mobile data or Wi-Fi to receive messages. The Government says about 95% of the UK population has access to 4G or 5G services and there are roughly 87 million mobile phones in the country.
Officials emphasised that no personal data, phone numbers or location information will be collected or shared during the test. Because the message is transmitted automatically through mobile networks, network operators do not need to hold or store recipients’ numbers in order to broadcast the alert, the government said.
Charities and some health experts have raised concerns about the potential harms of a sudden loud alert. Campaigners for victims of domestic abuse warned that a conspicuous siren and on-screen message could expose hidden or covertly carried devices used by people seeking help from abusive partners. The Government said it is engaging with domestic-violence organisations ahead of the test and reminded people that they can opt out if they believe remaining silent is necessary for their safety.
Medical specialists and researchers have noted that an unexpected alarm can trigger a strong acute stress response in some individuals. One study cited in public discussion found heart rates in participants rose from an average of about 74 beats per minute to roughly 111 beats per minute following alarm stimuli, and experts warned that a rare extreme reaction could pose health risks to vulnerable people. The Epilepsy Society also cautioned that loud noises may trigger seizures in susceptible individuals.
The Government has provided guidance for anyone who wishes to disable emergency alerts on a device. On an iPhone, users can open Settings, select Notifications and turn off "Severe Alerts" and "Extreme Alerts" at the bottom of the menu. On most Android phones, users should search the device settings for "Emergency Alerts" and switch off the relevant severe or extreme alert options; manufacturers may use alternate names such as "Wireless Emergency Alerts" or "Emergency Broadcasts." The government website advises users to contact their device manufacturer if alerts persist after opting out.
Emergency Alerts have been used in several real incidents since the system’s launch in 2023. Officials said the system was deployed to deliver warnings in Scotland and Northern Ireland during Storm Éowyn earlier in 2025, reaching about 4.5 million people, and was used in Plymouth last year to help evacuate more than 10,000 residents after an unexploded Second World War bomb was discovered.
Authorities have sought to minimise disruption from the test. Public information campaigns and signage have been placed across motorways, public transport hubs, museums, GP surgeries and cultural venues to warn people in advance. The Globe Theatre said it will pause a performance of Shakespeare’s Twelfth Night to avoid disruption when the alert is broadcast.
The UK’s system mirrors emergency-alert frameworks used in other countries. Japan operates a sophisticated nationwide network — J-ALERT — combining satellite and cell-broadcast technology to warn of earthquakes, tsunamis, volcanic activity and missile threats. South Korea frequently uses cell broadcast to notify citizens about weather events and civil emergencies, while the United States uses Wireless Emergency Alerts with a distinctive sound and vibration pattern.
Drivers were reminded that it is illegal to use a hand-held device while driving; officials advised motorists who receive the alert to pull over somewhere safe and legal before attempting to read the message. The Government reiterated that the test will only run for around 10 seconds and that the exercise aims to ensure the system is ready to deliver urgent warnings should a real emergency occur.