Together, Three and O2 boast the biggest mobile subscriber base in the UK, putting further pressure on EE and Vodafone. BT, however, is working on a plan of its own for UK mobile domination. The company, which sold off O2 for £17.7 billion almost a decade ago, is currently in talks with Orange and Deutsche Telekom to buy EE. The deal is expected to cost £12.5 billion and would give BT's credentials as a quad-play provider a major boost in the UK. In the meantime, the company is readying a new mobile service powered by EE's network. It's not the same as actually owning EE's infrastructure and customers, but regardless, such a move should give Sky something to think about. Sky, meanwhile, is preparing to counterpunch with an O2-powered mobile network in 2016.

Exactly when all these deals will go through isn't clear, but it's obvious that we're on the cusp of a major sea change in the UK telecoms industry. We won't know the winners and losers for some time, but renewed competition could be good for the consumer, and ultimately lead to better prices when you're next shopping for a new contract.