I bought an Iphone 3G on Craigslist last night to use on T-mobile. When I got the phone it was restored to factory settings so I took it home, plugged it into Itunes, and set it up. Upon connecting it to Itunes it said your phone is unlocked. Now, the guy who sold it to me said he originally bought it on Ebay from Australia. Does that mean its 'factory unlocked'? Everything has worked fine since I put my T-Mobile SIM card into it except MMS. Looking online for solutions I've found that people recommend downloading 'Legacy' through Cydia but my Iphone isn't Jailbroken. So I have no Cydia app. I don't necessarily want to Jailbreak but if I did could I do it from firmware 3.1.3?