Mobile phone users were unable to make or receive phone calls on Tuesday night after the Orange network was affected by a fault.
Orange said only a small number of customers had been affected
The firm said only 6% of its users were affected by the fault, which developed during the afternoon.
Engineers worked during the evening in an effort to rectify the fault and restore service.
The Press Association news agency quoted one user who said he had been told that 65% of the network was down.
Former telecoms analyst Chris Godsmark said his network
coverage had failed at around 7pm.
"I have been an Orange customer for six years and I spend between £100 and
£200 a month," he added.
"I would not call this a trivial fault and I'm very angry about it."
An Orange spokesperson said: "We can confirm that unfortunately a small
number of Orange customers are currently unable to make or receive calls from
the Orange network.
"This is due to a minor fault which occurred at 3.43 this afternoon with one
of our home location registers.
"Engineers are rectifying the fault and steps are being taken to minimise the
impact on customers and to restore normal service as soon as possible."
Orange said: "I can confirm that it is not 65% of our customers affected by this minor fault."