Emergency alert test review confirmed after ‘small number’ of mobile users excluded

Mobile network operator Three has confirmed it is working closely with the government to ascertain why some of its customers failed to receive the UK emergency alert test text as planned on Sunday 23 April 2023.

The Cabinet Office National Situation Centre said in a statement that every 4G and 5G device across the UK would receive a text at 3pm, as part of a trial run of the government’s emergency alerts service.

However, in the wake of the trial text being sent out, it has emerged that some mobile phone users across the UK with compliant devices did not receive the message, with Three UK customers appearing to be disproportionately affected.

In a statement on its Twitter page, Three UK said: “We’re aware that a number of customers have not received the test alert. We’re working closely with the government to understand why and ensure it doesn’t happen when the system is in use.”

A review of the test is underway to ascertain why a “small proportion of mobile users on some networks” were excluded from the test, Computer Weekly understands.

In a statement to Computer Weekly, a government spokesperson confirmed the review, and 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 operators to review the outcome and any lessons learned.”

The emergency alerts service is a new addition to the government’s toolkit of measures that are intended to bolster national resilience during the onset of situations – such as extreme weather events – that pose an imminent risk to life.

Similar systems are known to be in operation in a number of other countries, including the US, Canada and Japan, and have been widely credited with saving lives.

The government mounted a sizeable awareness campaign in the lead up to its emergency alert test message being sent, which was distributed using a mobile broadcasting system that relies on cell towers rather than SMS technology.

The message was also accompanied by a 10-second siren-like sound and vibration to alert phone users to the fact it had been delivered to their devices.

In the lead up to the test message being sent out, deputy prime minister Oliver Dowden said the system would make it easier for the government to deliver on its top priority, which is keeping citizens safe.

“The government’s number one job is to keep people safe, and this is another tool in the toolkit for emergency situations, such as flooding or wildfires, and where there is a genuine risk to life,” he said. “So, it really is a sound that could save your life.”

“I would encourage people to remember that today it is just a test; there is no need to take any action and you can simply swipe it away as you would any other message you receive.”