I am interested in purchasing an iphone 3GS, currently locked to a Vodafone network. How easy is it to get this unlocked to take any SIM card and are there any disadvantages to me buying this compared to a factory unlocked phone? There is no vodafone network where I live (C.I.). I do not wish to jailbreak the phone, just unlock. I've checked online, but I can't see anything for Vodafone. Thanks.