Thousands of people in the UK have been left unable to make or receive phone calls due to outages across the Three network.

Downdetector, a website that tracks outages, showed more than 10,000 reports of issues across the mobile network on Thursday.

Customers using smaller mobile companies Smarty and iD Mobile have also been affected because their providers use Three’s network.

Three’s support team has been advising people that it is “working hard to resolve this as soon as possible” but that it does not “have a timeframe” for a fix. But in an update at 6pm, iD Mobile told its customers via its website that “3UK engineers have identified and isolated the suspected issue”.

Three has about 10.5 million customers in the UK, with many sharing their frustrations on social media about the disruption caused.

One person said they had “missed a medical appointment” as a result of being unable to receive calls, while another said their daughter had been left “stranded”.

It is unknown if customers will be able to claim compensation for the issues, with Ofcom advising on its website that refunds “may be appropriate”.

The Competition and Markets Authority gave the green light to Three’s merger with former rival Vodafone in a £16.5bn deal last month.

In a post on X, Three said: “We’re aware of an issue affecting a small percentage of voice services, our team are working hard to fix this as soon as possible. We’re really sorry for any inconvenience caused. Data services and 999 calls are unaffected, please bear with us.”

Also posting on X, iD Mobile told customers: “We’re aware of a network wide issue affecting services, unfortunately we’re unsure when this will be fixed. However, we’re reporting this to our teams and working to resolve this as soon as possible. We apologise for any inconvenience caused.”