I want to buy an iPhone 4 and the carrier is Fido. I am currently on Rogers right now. I heard that sim cards with Rogers and Fido can be interchangable? So can I put my Rogers sim card into the FIDO iPhone 4 and use it? If that doesn't work, how can I use my rogers simcard in a FIDO iPhone 4? It is on the lastest firmware says the person that is selling to me. He said it can be downgraded and then unlocked? Is this true? Also does jailbreaking/unlocking slow down the iPhone? P.S. I will be cutting my simcard into a microsim, is this a bad idea?