This step-by-step guide and tutorial will show you how to unlock your iPhone 3GS running OS 3.1 using UltraSn0w. This is a very simple method that requires only a few steps.

Step 1: You have to jailbreak your iPhone 3GS by following one of these tutorials.

Step 2: Once jailbroken, follow these steps:

  • Launch Cydia.
  • Add the following source to Cydia repo666.ultrasn0w.com (note there is a “0″ in sn0w, not an “o”).
  • After installing this source in Cydia, search for “ultraSn0w”.
  • Install UltraSn0w and reboot your iPhone.

Tha’ts as simple as that!