I had unlocked the att 8310 a couple of weeks ago for myself, but I went back to my 8320 and gave the 8310 to my wife, now she can't get her email to register wit the phone, but I had mine register wit it when I had it, can't figure out how to fix it!!! help please
Sorry for the misunderstanding. ATT may or may not help you; they helped me with an 8320 problem, but I'm a customer. Actually, TMO helped me as well, even though I ditched them for ATT.
Ultimately (with both companies), I had the same problem. Neither of them could find my IMEI registered in their system, so eventually talked to RIM themselves. On the second try, the RIM rep figured out the problem and unregistered the old PIN from my BIS account.
You can actually have multiple PIN numbers associated with one BIS account, so once I nailed down the problem, the solution seemed pretty trivial.
Good luck and let us know how it goes.
By the way, did you actually call TMO and tell them you were switching devices? If not, you may want to try that before going the lengthy route.
Good luck, and good thing both companies have good customer service.