Mobile network investigates why users didn't get emergency alert

The mobile network Three said it was investigating why many of its users failed to receive an emergency alert yesterday from the government, in the first nationwide test for the UK's new national warning system.

- Alex Hern, Sammy Gecsoyler

The alarm was scheduled to sound at 3pm on all mobile devices connected to the UK's 4G and 5G networks, but while the piercing, 10-second tone did arrive for millions of people, and up to a minute early for some, Three users reported en masse that they did not receive it.

"We are aware that a number of customers have not received the test alert," a Three spokesperson said. "We are working closely with the government to understand why and ensure it doesn't happen when the system is in use."

A government spokesperson said: "We have effectively completed the test of the UK-wide emergency alerts system, the biggest public communications exercise of its kind ever done. We are working with mobile network operators to review the outcome and any lessons learned."

A very small proportion of users on some mobile networks had not received the message, a government source said.