Dumb question but.. I'm getting the GNex and I want to sell my DX. Since they don't have SIM cards, how does ownership actually change? I'll SBF and format the card, but I've done that before and all you do is turn it on and activate. I'm just curious how the phone is linked to my account/number. I'm guessing once I activate the GNex, they the Droid won't work easily activate anymore?