Everything Everywhere, the largest mobile operator in the UK with more than 27 million customers, intends to introduce the unnamed new venture in the UK "later this year".
It is thought that the initiative could be down to today's ruling by Ofcom that Everything Everywhere can start offering superfast 4G services to UK consumers from September 11.
The decision has been criticised by rival mobile operators such as Vodafone and O2 over concerns that it will give Orange and T-Mobile a competitive advantage in the 4G market ahead of a major spectrum auction.
There had perviously been speculation that Everything Everywhere, the joint venture of Orange and T-Mobile in the UK, was preparing to drop its original mobile brands in favour of a new overall identity.
However, the company has insisted that it remains committed to retaining Orange and T-Mobile as separate brands.
"Everything Everywhere confirms that we are planning to launch a new brand in the UK later this year," said a statement.
"This new brand will sit alongside our existing brands Orange and T-Mobile. We will reveal more information on our exciting plans in due course."
This approach makes good business sense for Everything Everywhere as millions of pounds have already been spent on establishing the two mobile brands in the minds of consumers.
It could also enable the firm to use the new brand to push 4G after it was awarded varied licences today to use its existing 1800MHz spectrum to offer the superfast LTE services.
Meanwhile, Everything Everywhere director of spectrum strategy Kip Meek has confirmed that the company is in talks with manufacturers about introducing mobile handsets that can receive the 4G signals.
Despite getting approval to launch 4G early, there are currently no smartphones available in the UK that feature the right antenna technology to receive Everything Everywhere's new service.
But speaking to TechRadar, Meek said: "There's always a question around the eco system [with new frequencies] and we hope to progressively to get more manufacturers to support 4G at the 1800MHz frequency.
"We hope to have more news about [4G devices] later this year, but we can't talk about it now."
There has been speculation that Apple's new iPhone will be able to support 4G at the 1800MHz frequency in the UK when it is announced as expected on September 12.
Considering the time required to gear the manufacturing process, that seems unlikely, but Meek confirmed that Everything Everywhere was talking to all the major players.
"We have a lot of discussions going on with multiple suppliers which we can't talk about much at the moment, but we hope to secure a very good collaborative relationship with the most successful supplier of phones at the moment," he said.
This would presumably indicate Samsung, which is currently the biggest seller of mobile phones in the world, ahead of Apple.