Superfast mobile broadband is to be launched in the UK later this year after T-Mobile and Orange got the green light to run 4G services.
Everything Everywhere, which owns the brands in the UK, has gained a head-start on rivals because regulator Ofcom has ruled the firm can use some of its existing spectrum prior to an industry-wide auction of 4G airwaves in 2013.
Vodafone attacked the decision but Ofcom said allowing Everything's request to vary its existing licence for 4G was in the best interests of consumers.
Everything said: "Consumers will soon be able to benefit from the much greater mobile speeds that 4G will deliver. 4G will drive investment, employment and innovation and we look forward to making it available later this year, delivering superfast mobile broadband to the UK."
It is expected that 4G will allow users to download an album in as little as 60 seconds or a movie in 10 minutes, compared with an hour or more for 3G.
Everything, which is jointly owned by Deutsche Telekom and France Telecom, is the UK's largest operator with 27 million customers and employs more than 15,000 people, including through more than 720 retail stores.
The company will be allowed to offer 4G from September 11, but has not specified when it will start the service. It has been rewarded for installing the necessary equipment for 4G since the start of the year, even though the bidding phase for the auction was not due to start until 2013.
The auction will give 4G access to at least 98 per cent of people across the UK with the equivalent of three-quarters of the mobile spectrum currently in use - some 80 per cent more than released in the 3G auction which took place in 2000.
Vodafone said: "We are frankly shocked that Ofcom has reached this decision.
"The regulator has shown a careless disregard for the best interests of consumers, businesses and the wider economy through its refusal to properly regard the competitive distortion created by allowing one operator to run services before the ground has been laid for a fully competitive 4G market."
With Everything in talks to sell some of its spectrum to rival operator 3, Vodafone said the balance of the 4G auction will "fundamentally change".
Thomas Wehmeier, principal analyst at Informa Telecoms & Media, said Ofcom's decision was a "major milestone" for the UK mobile market and a vindication of Everything's decision to invest in readying the ground for 4G.
He added: "Everything now has a golden opportunity to establish an early lead in the UK's 4G market, but it will only be able to exploit this window if it is able to build a successful launch strategy.
"The most successful 4G operators globally, including in the world's most advanced 4G markets of the United States and Korea, have been those that came out of the traps quickly and built their networks out extensively."
He said a critical task will be to convince device manufacturers to build smartphones for Everything's network.
Mr Wehmeier said: "You can build the network, but without the right devices the customers cannot and will not come."
Meanwhile, Everything declined to confirm reports that it will replace the Orange and T-Mobile brands from next March.
A spokesman said: "It is well known that we ran a brand review last year. The outcome of that brand review is confidential.
"However, what we can say is that we remain committed to our hugely successful brands Orange and T-Mobile and continue to invest in them for the foreseeable future. Any suggestion otherwise is entirely speculative."
Everything later said it planned to launch a new brand to operate alongside Orange and T-Mobile before the end of this year.