On Sunday, April 23, the emergency alert system was scheduled to be tested on mobile phones and tablets - but for many across Somerset, their phones remained silent.

The government alert was set to play at 3pm on Sunday. Many phones emitted a siren sound and displayed an on-screen message

The system is designed to give advanced warning of a danger to life near your location. In the event of a real emergency, it would send advice about how to stay safe.

However when some people received the message early, others late, and many didn't get it at all.

When the siren was tested on Sunday, just over half of pub-goers in the Iron Duke on Fore Street managed to successfully receive an alert, a reporter from the Wellington Weekly observed.

There were complaints across social media from people whose phones had not received the message - and the reasons have now been revealed.

Mobile phone which use the Three network did not receive the message. The mobile network said they are working with the government to resolve the issue.

Other phones weren't compatible with the alert message. For Android users to receive an alert message, they need to be running the Android 11 operations system or a more recent version. iPhone users need to be running OIS 14.5 or a more recent version.

Some people didn't receive the message because they were not connected to a 4G or 5G network - which is required for the message to transmit.

Welsh speakers complained after their emergency alert featured a typo in the on-screen message.

It is also thought some users on the 02 network also failed to receive the alert.