I'm about to purchase an AT&T Nexus One. I currently have an iPhone 3gs and I plan on selling the phone I like the least. If I go with the Nexus, do I just sell my iPhone on ebay without a SIM or should I get a new one from AT&T and sell the iPhone with the included SIM. I have a 32gb 3gs that is on 3.1.3 and jailbroken with Spirit.