At 3pm on Sunday, 7 September the Government will be testing the UK’s Emergency Alerts system. An emergency alert will appear on your 4G or 5G phones and tablets, a siren will sound and your device will vibrate. You will not need to take any further action.
The testing ensures the system is functioning correctly, should it be needed in an emergency.
You can find out more information about the tests on the Government website 
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