Vodafone is working to restore SMS and internet services to around 3.2 million customers following a break-in last night.
The company said that it has already restored voice services after thieves stole specialist networking hardware from one of its technical facilities, and is hoping to restore SMS and internet services later this afternoon.
"We had a break-in last night at one of our technical facilities, which resulted in damage done to some of our equipment," the company said in a statement today.
"This means that some customers may be experiencing temporary loss of voice, SMS and internet services. We are working quickly to restore these and will be back to normal as soon as we can. There has been no impact on the privacy of customers' data."
It is not clear whether the theft was a result of industrial espionage or sabotage, and raises questions over the tightness of security at Vodafone.