okay so heres the deal..
my friend got her att pearl unlocked and gave it to me...
tmobile told me that was perfectly fine and when i get it to just download the software and manager from their site. i have done this several times, but once i plug in my phone and try to update the software it says

"The blackberry desktop software does not have blackberry device software for the device that you have connected to the computer. contact your wireless service provider."

Has anybody had this problem?? I downloaded the right software so I dont know what the problem is

You need to delete vendor.xml file - T-Mobile software otherwise can not be installed on AT&T phone. Take a look at http://www.blackberryforums.com/gene...2-1-107-a.html
it has very good instructions on how to do it.

George

Correct. Delete the "vendor.xml" file. It can be found at c:\program files\common files\research in motion\apploader

Once you delete it you will be prompted to upgrade when you plug in and run Desktop Manager.

Note: it's not necessary to upgrade the OS in order to use your ATT Blackberry on TMobile. You will have the latest OS, though.