Millions of mobile phones across the United Kingdom have suddenly emitted loud siren-like sounds during operator tests of the national emergency alert system. These tests, distinct from the major public alerts in 2023 and 2025, serve a crucial but often misunderstood purpose. This story of the UK’s life-saving alert infrastructure reveals how engineers keep the system ready for real emergencies. Therefore, let us explore everything you need to know about operator tests and why your phone might ring unexpectedly.
The government launched the Emergency Alerts system in March 2023, following successful pilots in East Suffolk and Reading [citation:5]. The system uses mobile broadcasting technology to reach nearly 90% of mobile phones in a defined area when there is an imminent risk to life. This journey through the testing process explains the difference between public tests and operator tests. The chapter of UK emergency preparedness this system represents has already saved lives during severe weather events and other dangerous situations.
What Are Emergency Alerts? The Life-Saving System Explained
Emergency Alerts are messages sent directly to mobile phones when there is a danger to life nearby. The government and emergency services use this system to warn the public about severe flooding, wildfires, terror attacks, or other imminent threats [citation:5]. The alerts provide clear instructions about how to stay safe and what actions to take.
The system works by broadcasting from cell towers in the vicinity of an emergency. Any compatible 4G or 5G phone within range of those towers will receive the alert [citation:3]. This technology means the government does not need your phone number to send you an alert. Consequently, your personal data remains completely private.
The UK has already used the system for real emergencies. Approximately 3.5 million people across Wales and south-west England received an alert during Storm Darragh in December 2024. A 500kg unexploded Second World War bomb found in a Plymouth back garden also triggered a warning in February 2024 [citation:9]. Therefore, the system has proven its value in protecting public safety.
Public Emergency Alert Tests: The Major National Drills
The government has conducted two major nationwide public tests of the Emergency Alerts system. The first test took place on April 23, 2023, at 3pm [citation:8]. Millions of phones across the UK received their first taste of the loud siren-like sound that would accompany real emergencies.
The second national test occurred on September 7, 2025, again at 3pm [citation:3][citation:4]. Tens of millions of phones successfully received the message, according to government officials. Prime Minister Sir Keir Starmer called the test “an important step in keeping people safe during national emergencies” [citation:4].
The test message reads: “This is a test of Emergency Alerts, a UK government service that will warn you if there’s a life-threatening emergency nearby. You do not need to take any action. In a real emergency, follow the instructions in the alert to keep yourself and others safe” [citation:3]. This message also includes links to advice on preparing for emergencies.
What Are Operator Tests? The Invisible Checks
Operator tests are separate from public national tests and serve a different purpose. Mobile network operators carry out these tests to assess improvements made to the system and ensure technical functionality. The government website confirms that you may receive an alert “if you have a phone that has operator test alerts turned on” [citation:10].
These operator tests are not alerting you of real danger. The alerts will always have “operator” in the title and will confirm that no action is needed [citation:10]. Consequently, engineers can verify that the broadcasting infrastructure works correctly without causing public alarm.
Unlike public tests, operator tests may not receive advance public notification. This occasionally leads to confusion among phone users who hear the siren sound unexpectedly. However, these behind-the-scenes checks are essential for maintaining a reliable emergency warning system.
What Happens When You Receive an Emergency Alert?
When you receive an emergency alert, your mobile phone or tablet will take several actions. The device will make a loud siren-like sound for approximately 10 seconds [citation:10]. It will also vibrate continuously during this period. The alert will appear on your home screen, similar to a low battery warning.
The alert will read out its content for accessibility purposes. This audio feature helps people with visual impairments understand the warning [citation:3]. The message will also include a phone number or a link to the GOV.UK website for more information.
The sound and vibration will stop automatically after 10 seconds. You can then swipe away the message or click ‘OK’ on your phone’s home screen [citation:8]. Therefore, the disruption to your day is intentionally brief.
Do Other Countries Run Similar Emergency Alert Tests?
Lots of other countries operate similar emergency systems and run regular tests. Japan and the United States have used these systems successfully for years [citation:3][citation:5]. Some countries test their systems monthly, such as Finland, while other countries test annually, such as Germany.
The UK system was modelled on successful schemes in Canada, Japan, the Netherlands, and the United States [citation:5]. These international precedents have widely credited the technology with saving lives during severe weather events and other emergencies.
The European Union required member states to introduce emergency public warning systems by June 2022 under Article 110 of the EU electronic communications code [citation:1]. Ireland is currently developing a more sophisticated cell broadcast system similar to the UK’s [citation:1].
Why Some People Didn’t Receive the Test Alerts
Not everyone receives emergency alerts, even during national tests. You will not receive alerts if your device is turned off, connected to a 2G or 3G network, on wifi only, or in airplane mode [citation:3][citation:10]. Some older devices are simply not compatible with the technology.
During the September 2025 test, some users reported technical issues. A BBC journalist received a garbled, distorted message instead of the proper alert text [citation:4]. The government responded that “where a message may have appeared incorrectly, this is likely due to issues with individual mobile handsets” [citation:4].
Compatible devices include iPhones running iOS 14.5 or later and Android phones running Android 11 or later [citation:10]. If your device meets these requirements but you still do not receive alerts, check your settings for emergency alert preferences.
What About Deaf, Hard of Hearing, or Blind People?
The government has designed emergency alerts with accessibility in mind. For people with hearing impairments, the vibration feature provides a physical notification [citation:4]. For those with visual impairments, audio and attention signals will inform you of the alert if accessibility notifications are turned on [citation:3].
During the September 2025 test, some hearing aid users experienced unexpected intensity. Julian from Lancashire told the BBC that his wife “literally ripped her hearing aids out and was incredibly distressed by the sound” [citation:4]. The government has committed to ongoing engagement with disability charities and campaigners [citation:3].
The government has also prepared general advice for disabled people and their carers during emergencies. You can find this information on the official GOV.UK website. Therefore, organisers continue working to improve the system for all users.
How to Opt Out of Emergency Alert Tests
Most people should keep emergency alerts switched on for their own safety. However, there are legitimate reasons to opt out. Victims of domestic abuse with a concealed phone may need to disable alerts to avoid detection by their abuser [citation:3]. The government recommends these individuals consult opt-out instructions on the official website.
To opt out of operator test alerts on Android devices, search your phone’s settings for ’emergency alerts’ and turn off ‘test alerts’, ‘exercise alerts’, ‘operator defined’, and ‘operator alerts’ [citation:10]. If you cannot see these options, open your phone’s calling app and enter *#*#2627#*#* using the keypad.
On iPhones, the settings can usually be found under ‘Settings’, then ‘Notifications’, then scroll to the bottom for ‘Emergency Alerts’ and ‘Test Alerts’. Depending on your manufacturer and software version, these settings may have different names [citation:10].
FAQs
What is the difference between a public emergency alert test and an operator test?
Public tests are nationwide drills announced in advance to prepare the public for real emergencies. Operator tests are technical checks conducted by mobile network operators to verify system functionality. Operator tests may have “operator” in the title and confirm no action is needed.
When was the last UK emergency alert test?
The last major national test took place on September 7, 2025, at 3pm. Tens of millions of phones received the alert across England, Scotland, Wales, and Northern Ireland. The first national test occurred on April 23, 2023.
Why did my phone not receive the emergency alert test?<brYou may not receive alerts if your device is turned off, connected to a 2G or 3G network, on wifi only, or in airplane mode. Older phones running outdated software may also be incompatible. Check your device meets the requirements: iOS 14.5+ or Android 11+.
Will I receive UK emergency alerts if I am on holiday abroad?
No. The system works by UK phone masts broadcasting an alert to compatible phones in range. If you have taken your phone to another country, it connects to local mobile networks and cannot receive UK alerts. Your phone also must be connected to 4G or 5G.
How do I turn off emergency alert tests?
Search your phone’s settings for ’emergency alerts’. For Android, turn off ‘test alerts’, ‘exercise alerts’, ‘operator defined’, and ‘operator alerts’. For iPhone, go to Settings > Notifications > scroll to bottom for Emergency Alerts options. Victims of domestic abuse should consult gov.uk/alerts for guidance.
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