How to unlock iPhone 4 (on 4.3.1) with Ultrasn0w 1.2.1
We have informed you about the availability of ultrasn0w 1.2.1 with the unlock support of iOS 4.3.1 that works with the old basebands. Here, we will guide you how to unlock your iPhone 4 or iPhone 3GS running on iOS 4.3.1 using ultrasn0w 1.2.1.
