In just a few days time, people across the UK will receive an alert to their phone with millions of the hand held devices set to go off by the end of this month.
On April 23, at exactly 3pm, millions of people will see a message appear on their phones alongside a siren-like alarm and vibration.
This should only last 10 seconds - unless you click ok and stop it sooner - and comes as part of a nationwide test of a new public alert system designed to be used in life-threatening situations including flooding and wildfires.
