Mobile operator Three experienced issues over the weekend leaving customers without service.
Customers had problems with receiving texts and making calls from midday Saturday until Saturday evening, with services running again by Sunday morning. Three advised customers to restart their phones if they are still experiencing issues.
The firm said: "We have been working through the night to fix a network issue which was affecting customers sending and receiving text and making calls. All services are now restored but some customers may need to restart their phones if they are still experiencing any issues."
"Some customers and non-customers may have received a message from an unknown sender," Three added. "Our advice is still to ignore all text messages that you deem incorrect. We apologise for any inconvenience caused to you."
IT Pro has asked what caused the issue and how many people were affected.
Customers expressed their annoyance on social media.
It comes after Three suffered a data breach in March, where some customers were presented with the telephone histories and personal details of other users. When some users logged into their account portal they found they were presented with the details of another customer. This included names, addresses and phone numbers for random strangers, as well as complete, time-stamped records of which numbers these people called and texted.
Three experienced another data breach last November, in which nearly 134,000 customers had their data accessed by criminals. The information accessed included customer's' phone numbers, how long they have been a Three customer, their handset type and whether they are a SIM-only or monthly contract customer, as well as whether their bill is paid by cash or by card. However, for 26,725 customers the breach potentially affected additional data such as their name, address, date of birth, email address, previous addresses, marital status and employment status.
