Vodafone has announced that it’s to sell DRM-free MP3 tracks from three of the four major labels – UMG, Sony and EMI – through its mobile and PC digital music stores. The deal covers a million tracks in all, including artists like Coldplay, Britney Spears, Duffy, Lady GaGa and The Fray. The tracks will be sold through the Vodafone Music Store, and customers who’ve already bought those songs in WMA format from Voda will be able to upgrade them to MP3 at no extra cost.That last detail is significant, given that Apple has been charging iTunes customers additional fees to upgrade their DRM’d files to iTunes Plus DRM-free ones. Voda has kept some details back – it only says that the DRM-free music will be available “through a number of Vodafone countries by the summer”.