I know I sound utterly clueless, but when you get an unlocked phone (like off E-Bay), what do you do to get it to work with your provider (specifically Cingular)? Would I have to fool around with a new SIM card or anything? I already have a Nokia 7160 with Cingular, and I want the 7210 or 6100. Basically, what's the whole process, from step one (buying the unlocked phone)? Any input would be really helpful, since I feel like I have to be walked through this. If there's already a post on this specific topic (I couldn't find one, but just in case I missed it), please let me know so no one's repeating him/herself. Thank you sooooo much!