On Sunday the government tested the emergency alert and millions did not receive the test message on their smart phones.
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.”
It has since been revealed that those who are using Three as their mobile provider did not receive the test message.
A spokesperson for the network said, “We are aware that a number of customers have not received the test alert.
“We are working closely with the Government to understand why and ensure it doesn’t happen when the system is in use.”
The Deputy Prime Minister Oliver Dowden said on Sunday the message alert will save lives.
Ahead of the test he said, “Our 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.
“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.”