Last month we reported that the German owners of Mobile Broadband operator T-Mobile UK, Deutsche Telekom, had come under pressing from two main shareholders to sell the operator ( here ). Today reports are starting to come in that the world's largest mobile phone firm by revenue - Vodafone , is considering a bid.The Financial Times reports that T-Mobile has an estimated enterprise value of somewhere between £2.55bn (€3bn) and £3.40bn (€4bn), though such a significant acquisition would raise an eyebrow or two among competition authorities. It's easy to see why when you look at the market shares involved:A combined Vodafone and T-Mobile UK operation would thus control 40% of the market, which is a lot of power for one operator to have; though it has already happened in France, Italy and Spain. There are also other considerations, such as the extensive network sharing agreement between T-Mobile UK and Three (3).Indeed some had long thought that a merger between Three (3) and T-Mobile looked more plausible due to their current arrangements, although so far we've seen next to no movement on that angle. It's worth pointing out that Vodafone recently combined with Hutchinson in Australia; Hutchinson also owns Three (3) in the UK.