It was only in June that we saw Virgin Media shaking up its regular mobile plans for UK residents. The carrier is back for another round, this time to serve the SIM Only customers who thrive on unlocked phones. Four plans starting from £12 ($19) a month all provide unlimited data and text messaging for bring-your-own-phone subscribers, with voice as the only real separating factor: the thriftiest callers get 150 minutes per month, while higher £15, &poun