On June 25, 2025, a significant outage on the Three mobile network left thousands of customers unable to make or receive calls, with many also experiencing issues with text messaging and mobile data connections.

During the outage, users reported over 9,000 issues on the Down Detector website, indicating the widespread impact of the disruption.

Three UK acknowledged the outage, stating that while data services were functioning normally, they were actively working to resolve the voice service issues.

Although reports of outages decreased later in the day, around 6,575 customers were still experiencing problems, primarily with voice calls and signal issues.

Many customers are demanding compensation for the disruptions, raising concerns about the network's reliability, especially following a previous outage a few months ago.

The outage affected users across the UK, with particularly high reports of issues in major cities such as Manchester, Birmingham, Glasgow, and London.

Other networks operated by Three, including Smarty and iD Mobile, also reported similar issues, prompting them to issue apologies to their customers.

The outage occurred shortly after Three's recent merger with Vodafone, which aimed to enhance network services but has not yet resolved current issues.

Despite Three's claims that 4G and 5G services were functioning normally, many users reported difficulties connecting to these services.

Some customers have threatened to leave the network due to ongoing service issues, with one individual stating they would not renew their contract expiring soon.

The impact of the outage has been significant, with reports of customers unable to make essential calls, including one parent who had to drive to a doctor's office due to the inability to call.

Customers were advised to use third-party messaging apps for making calls during the outage, as Three worked to resolve the issues.