The 3 user base is going to get a big boost now that the Ofcom ruling over lowering termination rates has been made, according to the carrier's Chief Executive Officer (CEO) Kevin Russell.
Mr Russell believes that his firm, which is the smallest of the UK's major mobile networks, will be able to expand "aggressively" following the assurance that mobile calls will be cheaper.
It was recently revealed that Ofcom, the industry regulator, has ordered that inter-network calling costs will be cut from 4.3p a minute to 0.5p.
This move will put millions of pounds back into the pockets of customers around the country, according to Mr Russell.
3 was a key member of the 'Terminate the Rate' group, which also included BT and other firms who wanted to see termination rates and mobile calling costs fall.
In under six months, the campaign had gathered support from over 100,000 individuals and organisations.
Opponents of the rule changes say that, in fact, the costs of mobile calling could stay the same as some networks will simply increase costs of other services in order to make up for the shortfall in their revenues.
O2's Matthew Key said: "Ofcom is moving one of the key elements in the equation and we can't just sit by and let this happen.
"Clearly, we need to change our business model to do something to compensate".