How to Unlock iOS 4.3 on iPhone 4, iPhone 3GS/3G with Ultrasn0w

Now iOS 4.3 can be unlocked using the existing version of Ultrasn0w provided that your iPhone 4, iPhone 3GS or iPhone 3G is already on unlockable baseband and moreover you have updated your device to iOS 4.3 using custom firmware while preserving the baseband.

Earlier it was reported that iOS 4.3 breaks Mobilesubstrate, which is required to run many Cydia apps, and Ultrasn0w which unlocks the devices. But iH8sn0w has just released a new version of Sn0wbreeze which fixes not only MobileSubstrate but also Ultrasn0w on iOS 4.3.

Here is complete step by step guide to unlock iOS 4.3 on iPhone 4, iPhone 3GS and iPhone 4 (baseband 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00).

Step 1: First of all cook a custom iOS 4.3 firmware for your device using the latest Sn0wbreeze 2.3 beta 4 and update your device using this custom iOS 4.3.

Sn0wbreeze 2.3 b4 also jailbreaks your devices but jailbreak is tethered boot at present meaning you’ll have to connect your iPhone with PC after every reboot. Sn0wbreeze 2.3 b4 also hacktivates the iPhone in case your are not on official carrier.

Download Sn0wbreeze 2.3 b4 from here (Download Link). The complete instructions to cook custom iOS 4.3 firmware are posted in our this post.

Sn0wbreeze 2.3b4 details are here:

ultrasn0w now works for basebands (01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00)
ultrasn0w is NOT compatible with the folllowing basebands! (02.10.04 / 03.10.01 / 04.10.01 / 05.14.02 / 05.15.04)
Upgrading your iPhone 3GS baseband to the 06.15.00 iPad baseband hack to unlock MAY cause you to lose your GPS!
Fixed minor GUI + iBooty bugs.

After jailbreaking your device follow the steps mentioned below to unlock your device.

Step 1: Launch Cydia from your device Springboard.

Step 2: Tap on Manage and select “Sources“.

Step 3: Touch on “Edit” and then on “Add“.

Step 4: You will be prompted to add the source URL http://repo666.ultrasn0w.com(its zero in Ultrasn0w) as shown in the image below.

Step 5: After the source has been added, use the Search option and type Ultrasn0w to search and install it.

Step 6: Restart iPhone after installing Ultrasn0w. You should now have unlocked iPhone 4 on iOS 4.3 GM.

This guide is posted for testing and educational purposes only. Please don’t try it if you don’t know what you are going to do.