3UK on Thursday revealed that its 4G subscriber base has reached 3.1 million, more than a third of its 8 million customers.

The mobile operator soft-launched its 4G network in Central London, Birmingham, Manchester and Reading in December 2013, extending coverage to a further 32 large towns and cities by February this year. It does not charge a premium for 4G, offering it at the same price as its 3G service.

On Thursday, 3UK said its 4G network now covers 48% of the U.K. population.

"The rollout of new capacity is progressing well and, most importantly for me, customer satisfaction is higher than ever," said 3UK CEO Dave Dyson, in a statement. "With an advanced 3G network already in place all our customers are able to benefit from a reliable and high-performing network."

The company aims to extend 4G coverage to 98% of the population in 2015. To help it achieve this ambition, 3UK is deploying 4G in the 800 MHz band, which is well suited for providing coverage indoors and over large areas.

"The addition of low frequency spectrum is just one part of our plans to expand 3UK's coverage and bring our network to more people in more places in 2015," Dyson said.