I currently have a Droid X2 that went for a swim so I'm looking to replace it. I still have unlimited data and do not want to lose it because that's all I really ever use. I want to get a HTC Thunderbolt but I will need a SIM card which I didn't need with the X2. Will this change anything about my phone plan? Will I need to sign a new contract and lose all that wonderful data? Thanks in advance!