I just sold my MPx200 on Ebay, and the buyer sent me this question, can someone please give me a reliable answer to give him? I don't really know the answer myself! I bought it with WM2002 installed, then I upgraded to WM2003 and bought and used an unlock code so it would work with Cingular after ATT was bought. The unlock code worked fine and it does work on my local Cingular plan (south Alabama), but I don't know if it will work for this guy, please help me out.
"I just won the bid for, and paid through paypal for your phone. In the description for the phone, you say that cingular will work with the phone. I have cingular, and I hope it will work. Also, will me being on the east coast make a difference? I bought a phone from someone on the west coast once, and it wouldn't work out here. I just hope when I put my sim card in the phone, It works. Thanks."
The MPx200 doesn't support the 850 band if I remember correctly, so if he's in an area where Cingular only offers 850 coverage, he might have a problem.
If you haven't already, you might want to post this question in the Cingular forum. The HoFo Cingular users there know the network inside/out.