Virgin Mobile will compensate customers after many were left unable to make calls, send text messages or use mobile data.
UK users of the mobile network voiced their frustrations about the fault on Tuesday morning.
Virgin Mobile said the disruption was due to a technical issue.
A spokesman said on Tuesday night: “We apologise for the disruption and inconvenience some of our Virgin Mobile customers have experienced today.
“This was due to a technical issue which we’ve now resolved.
“We will be compensating our customers for the loss of service and will let them know the details shortly.”
Many users complained the issue meant they could receive texts and calls but could not make them and could not access the internet through mobile data, however the fault appeared to affect some customers in different ways.
Service outage tracking website Is The Service Down said complaints about the issue on social media began at 8.20am, with comments surging shortly after 11am and into the afternoon.