Unlock iOS 4.3.3 on iPhone 4, 3GS Using Ultrasn0w 1.2.3 [Step-by-Step Guide]

Today Ultrasn0w 1.2.3 has been released, and it was much needed because current version of the Ultrasn0w 1.2.2 was not compatible with iOS 4.3.3.  It should be emphasized that this is NOT a new unlock for the new basebands but it fixes the issues on already compatible basebands namely: 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00.

Here is a guide of unlocking the iOS 4.3.3 on iPhone 3GS and iPhone 4 using the Ultrasn0w 1.2.3 after untethered jailbreaking iOS 4.3.3 either using PwnageTool 4.3.3 (on Mac) or Sn0wbreeze 2.7 (on Windows). If your device is not jailbroken on latest iOS 4.3.3 then please follow these guides to do so (while preserving the baseband) for both Windows and Mac:

• Untethered Jailbreak iOS 4.3.3 & iOS 4.2.8 On Verizon iPhone 4 & Preserve Baseband For iPhone, iPod touch and iPad Using Sn0wbreeze 2.7 – [Windows Guide]
• Jailbreak iOS 4.3.3 Untethered & Preserve Baseband on iPhone, iPod touch and iPad Using PwnageTool 4.3.3 – [Mac Guide]

Before we proceed any further please make sure you understand the following points:

• Ultrasn0w 1.2.3 supports unlock for basebands (01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00).
• ultrasn0w 1.2.3 is NOT compatible with the following basebands (02.10.04 / 03.10.01 / 04.10.01 / 05.14.02 / 05.15.04).

iPhone 3GS Users: Update iPhone 3GS to 06.15.00 Baseband for Unlock:
iPhone 3GS is required to be jailbroken with 06.15.00 baseband for Ultrasn0w 1.2.3 unlock . Follow the complete guide posted here to update your iPhone 3GS baseband to 06.15.00 and jailbreak it on iOS 4.2.2 before proceeding further.

Now we move to the actual process:

Step 1: First you need to be jailbroken on iOS 4.3.3. Follow our guides to do untethered jailbreaking iOS 4.3.3 using PwnageTool 4.3.3 (on Mac) or Sn0wbreeze 2.7 (on Windows) [see links in the start of the guide].

Step 2: Now you are jailbroken on iOS 4.3.3 you need to unlock the phone using the Ultrasn0w.

• Load Cydia on your iPhone.
• Push the Manage tab at the bottom.
• Now push on the Sources.

Step 3: Now tap on the Edit and then tap on Add. Now you will get a prompt to enter a URL source (see the screenshot below). Type the http://repo666.ultrasn0w.com and tap on Add Source to add this repo if you haven’t already.

Step 4: Cydia will now automatically update your sources by following a series of automated steps. When the installation is complete search for “ultrasn0w 1.2.3” in Cydia, and install it. It will automatically unlock your iPhone so that you can use it with any carrier without any further action.

Step 5: Finally reboot your  iPhone (using the normal “slide to power off” swipe), and you should now have a completely unlocked iPhone 4 or 3GS, running iOS 4.3.3!