Millions of mobile phones across the UK will vibrate and sound a siren for 10 seconds at 3pm on Sunday as part of a nationwide test of the emergency alert system. The alert will display a message confirming it is a test.
The government has stated that not all devices will receive the alert, including older phones and those not connected to 4G or 5G networks. Phones that are switched off or in airplane mode will not sound the alarm.
The 10-second duration was designed to balance comprehensive testing with reducing inconvenience to the public. The system has been described by Cabinet Office minister Pat McFadden as a 'national fire alarm' that requires regular testing.
The alert has already caused some disruption, with the Glasgow derby between Celtic FC Women and Rangers Women's FC being pushed back to 3.05pm to accommodate the test. The system has been deployed five times since its first test in April 2023, with the largest use in January this year during Storm Éowyn.
Victims of domestic abuse with concealed phones can opt out of alerts, but switching a handset to silent will not prevent the alert. The system broadcasts from mobile phone masts in specific areas, so tourists with non-UK numbers will also receive the alert.
The National Preparedness Commission said the test is an important part of preparations for threats from extreme weather to national security challenges. Chair Toby Harris noted the increasing need for such preparedness given the volatile international situation and extreme weather events.
