O2's 4G network now covers one-third of the UK population indoors, it has been revealed.
The mobile broadband provider claims next-generation services are now available in 191 towns and cities across the country.
In terms of outdoor coverage, 41 per cent of the UK population is able to take advantage of O2 4G mobile broadband.
The company launched its next-generation network in August 2013 and since then has attracted more than a million subscribers.
Those customers used more data in the 4G network’s first six months than the entire O2 network carried between 2000 and 2008, the firm revealed.
O2 said this demonstrates "the unprecedented demand" for fast and seamless data services in the UK.
The company is planning to further extend the reach of its super-fast mobile broadband network through an infrastructure modernisation programme.
Approximately 25 per cent of O2 2G and 3G masts will be upgraded by the end of 2014.
In addition, more than 200 areas across the UK will gain 3G coverage for the first time, allowing an increasing number of people to take advantage of mobile broadband.
Derek McManus, Chief Operating Officer of Telefonica UK, said the company has undertaken "the fastest network roll-out in the history of the company" since introducing 4G services in the summer.
"This year we’re continuing that roll-out and concurrently modernising our 2G and 3G networks," he stated.
Mr McManus said building a great network is not just about bringing faster speeds to people who already have coverage.
"It’s vital that we also bring seamless coverage to people that have never had it before," he stated.
"Investment in all layers of our network is key to ensuring customers receive a great experience, whether that’s in streaming live goals in the pub or receiving critical business information."
Mr McManus added that O2 is investing the equivalent of £1.5 million in its network every single day, offering seamless connectivity for customers across 2G, 3G, 4G and Wi-Fi.
"We remain focused on delivering an experience that exceeds our customers’ expectations," he stated.