The iPhone Dev Team has updated the UltraSn0w unlocking tool to support iOS 4.3.1. Please note that this is not a new unlock and is only an update for the older basebands. Currently the only way to have an unlocked iPhone on iOS 4.3.1 is to preserve an old unlockable baseband through a custom firmware IPSW upgrade using something like PwnageTool or TinyUmbrella. This updated UltraSn0w also fixes the signal bar issue (only displaying 1 bar) for those who aren’t using the unlock but retain an older baseband intentionally. UltraSn0w is compatible with iPhone 4 baseband 01.59.00 and iPhone 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04 and 06.15.00You can get the update for UltraSn0w in Cydia.
I will have some video tutorials up soon on how to update to iOS 4.3.1 and preserve your baseband so that it is compatible with UltraSnow
I cannot seem to get my tmobile to work on my iphone 4
I have it unlocked with ultrasnow.
Do I need to download something else in cydia for tmobile to work?