UK mobile networks are going through a dramatic update with all of Britain’s biggest operators switching off ageing 3G technology and transferring all of their time and effort into boosting 4G and 5G services. Some providers - including EE and Vodafone - have already ended access to 3G, and O2 is now following with its own closure.

The popular network says it began hitting the 3G off switch back in April, with Durham the first to lose access. More areas are slowly losing access to this system, with it being closed completely by the end of the year.

With the switch-off picking up pace, O2 is now urging customers to check their phones to make sure they aren’t affected in the future.

Some older smartphones can’t connect to fast 4G and 5G, and once the 3G plug is pulled, it could leave customers blocked from access to mobile data and vital services such as WhatsApp.

Explaining more, O2 said in an email seen by Express.co.uk: "You may currently have a device that’s not fully compatible with the UK’s 4G or 5G network. After the switch off, you could experience a drop in call quality and be unable to access mobile data, including the internet and messaging apps like WhatsApp."

To help keep users connected, O2 has also supplied a link with reveals all the phones that could soon lose their connection.

Once clicked, customers can simply add their IMEI model number - which can be found in the settings - to see if it will continue to work in the future.

Why is 3G being turned off?

There was a time wihen 3G ruled the roost. Lauched in the UK all the way back in 2003, it finally offered the ability to browse the web and even stream away from home.

Sadly, 3G has been superseded by 4G and 5G networks over recent years, with the 3G network carrying less and less traffic.

“By focusing our investment on 4G and 5G, we’ll be able to further expand and upgrade services, while being more energy efficient and better for the environment,” O2 explained.

“Plus, it means you’ll be able to benefit from quicker download speeds and higher quality voice calls.”

When will the full 3G switch-off happen?

O2 says its full 3G switch started in April 2025, in Durham, and will continue across the UK throughout the rest of the year.