The O2 network has been hit by a technical problem so customers across the UK are unable to use 4G.
The issues started at about 5:30 am this morning ( 6 December )
A statement on their website said engineers are investigating issues related to data problems.
It said: “Our technical teams are investigating reports of issues when using data. Voice calls are working OK. Our technical teams are investigating.
“We apologise for any inconvenience.”
Customers have vented their frustration at not being able to access the internet on their phones.