http://www.blackberryforums.com/rim-...ry-device.html
You don't need TMobile to get software for the 7105t. You can load any carrier's OS to the device. Just pick the latest one and install it. Make sure after installign the DM and the OS to the PC that you delete the vendor.xml file. Then the OS will load as normal.
BlackBerry Operating System Downloads - BlackBerryFAQ