Emergency alert to be sent to smartphones
- The British Polio Fellowship

- Sep 1
- 2 min read

The UK government will be carrying out a nationwide test of its emergency alert system at 3:00pm on Sunday 7 September. During the test, compatible mobile phones will vibrate and emit a loud siren for 10 seconds, even if set to silent. A message will also appear on the screen.
These alerts are designed for life-threatening emergencies, such as extreme weather events or terror attacks.
Although the alert system has been trialled regionally five times, a nationwide test in 2023 revealed several technical problems. Some people received the alert too early, others not at all, and some got multiple notifications. Users on the Three network were especially affected. The government later confirmed that around 7% of compatible devices failed to receive the alert.
Those issues have been reviewed, and the new test aims to ensure the system now functions properly. It also hopes to familiarise the public with the alert process, as seen in other countries such as America and Japan.
Out of approximately 87 million mobile phones in the UK, only smartphones connected to 4G or 5G networks will receive the alert. Devices on 2G or 3G, or older phones, are not compatible. Phones must be switched on and not in airplane mode, but they don’t need to be connected to mobile data or Wi-Fi.
The emergency alert system has already been used in real incidents:
During Storm Eowyn in January 2025, 4.5 million alerts were sent in Scotland and Northern Ireland.
A month earlier, 3.5 million were sent during Storm Darragh in England and Wales.
The system also supported the evacuation of over 10,000 residents in Plymouth after a 500kg World War II bomb was discovered and safely detonated at sea.
While the government encourages people to keep emergency alerts enabled, it has published an opt-out guide for those in vulnerable situations.








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