At this point of time, when we are waiting for a proper jailbreaking tool to jailbreak iOS 4.0 on all iPhones and iPod Touches, the iPhone dev team has released UltraSn0w 0.9.3 which is the first iOS 4.0 unlock tool. This tool can work with basebands 05.13.04 and 05.12.08, meaning those users who upgraded iOS 4.0 preserving baseband can also unlock iOS 4.0 with Ultrasn0w 0.93. Check out our step-by-step guide to unlock iPhone 3Gs and iPhone 3G on iOS 4.0 using ultrasn0w.

How to Unlock iOS 4.0 Baseband 05.13.04 on iPhone 3G/3GS?

  1. Jailbreak iOS 4.0 on iPhone using RedSn0w (coming soon)
  2. Once jailbroken, start Cydia and go to Manage section
  3. Now click on sources and click on edit to add following repository
  4. Now search for Ultrasn0w 0.93 and click on install
  5. Let Ultrasn0w 0.93 complete unlocking procedure. Once your iPhone will reboot you can enjoy your unlocked iPhone 3G/3GS 4.0 with your favorite carrier. [via]Blogsdna