Ultrasn0w 1.2.1 fix all these bugs. But you have to know that ultrasn0w 1.2.1 isn’t a new unlock, it will allow users to unlock iPhone 4, 3GS on these basebands only (04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00, and 01.59.00).
So who relies on ultrasn0w unlock and want to jailbreak his device on iOS 4.3.1, he MUST use PwnageTool 4.3 (Mac) or Sn0wbreeze 2.5 (Windows) to preserve their unlockable baseband while upgrading to iOS 4.3.1.
[machackpc]