I currently have a Droid X and got the SGS 3 to keep my unlimited for at least another two years. Now that I got it, I want to sell it so I can get another phone in the future. My question is, do I have to do anything such as activate the phone or do something with the SIM card before selling it? I have read online that I should keep the SIM card since it is tied to my account and I can use that when I get a 4G phone. Is that true? As far as activating it, if I do have to activate it then how can I do so without using the phone? To reactivate the X, I can just do *228, right? Any other concerns I should have before selling it?