At about 3pm this afternoon, people across the UK were send their first emergency alert as the Government tests the new alarm system.
Millions of phone gave off an extremely loud siren sound, even if the phone was on silent, for 10 seconds. Coming a minute earlier than planned, the alert gave many people a fright - but some were left baffled when they didn't get it at all.
It's possible to turn the alerts off and there are some people who won't get them, but many who were expected to be a part of the trial were left without.
