Customers are experiencing issues with access to their mobile networks, with outages reported across the UK.
Those affected include users of Vodafone, O2, EE, Three and Tesco Mobile.
Many customers have reported being unable to use the UK mobile networks for voice call connections, though they can still text and use mobile data.
Problems surfaced on the networks just after 5pm today but have since improved, according to outage monitor website Downdetector.
Vodafone said in a statement this evening: “We’d like to apologise to any customers who struggled to make phone calls this evening.
“We had an incident at around 17.20, which was fixed at 18.10. The service is now fully back to normal. Any customer struggling to make a call, should quickly turn their phone off and on again to restart. We apologise for any inconvenience caused.”
A spokesperson for Vodafone told the BBC earlier this evening that it was caused by a change it had made to block a range of numbers making spam calls, which then had a “knock-on effect” on the ability to make voice calls for some users.
A Three spokesperson said: “There was a fault on another network that meant that calls were unable to connect. There was no fault on the Three network at any time.”
An O2 spokesperson said that its customers were unable to contact Vodafone users for a time, but that there was no issue with its own network.
An EE spokesperson said: ““Following an issue on the Vodafone network this afternoon, we know that some people couldn’t connect to some Vodafone mobiles. There’s no issue with the EE network.”