Have had a blackberry curve for a couple of year now. Always been good but want to upgrade to a 9900 for the GPS and 3G capabilities. Virgin are a little over priced on their contract and handset prices (currently paying around 10quid a month for blackberry tariff). Looking at buying a SIM free 9900 and just swappiong the SIM card over from my curve, keeping the same tariff and phone number. Will this work? Any de-registration / registration of Blackberry services required?