I just purchased an unlocked SMT 5600 off of ebay. I was curious to the steps I should take in order to use on the Cingular network? I still have an ATT TDMA plan and have not migrated yet. Do I just go to the Cingular store tell them I have an ulocked phone and want to migrate to a cingular plan. Also, is there a way that a carrier can "relock" your phone once you activate their sim in the phone?