During the first nationwide test of the UK government's new public alert system, tens of millions of mobile phone users received a loud alarm and message about the service. The alert, designed to warn of life-threatening emergencies nearby, was sent to every 4G and 5G device in the country. While the alert was set to go off at 3 pm on Sunday, some received it a minute early. The alarm and vibration lasted for about 10 seconds, with instructions for users to swipe it away if they didn't need to take action. The aim of the test was to familiarize the public with the alerts so that they would be ready to respond in the event of future crises.