UltraSn0w version 1.2.1 was released only moments ago and for those of you who would like a helping hand with using it, we have put together a quick how to guide. In this guide you will learn how to unlock your iPhone running the iOS 4.3.1 firmware. Unfortunately unlocking is not as easy as just installing UltraSn0w, if you have never unlocked prior to this moment you will most likely be unable to unlock your iPhone. This is because UltraSn0w only supports several older baseband version that you will need to check, (Go into Settings > General > About)  and see if you have a supported baseband version by comparing your version number to the list below.

Supported Basebands:

• 01.59.00
• 04.26.08
• 05.11.07
• 05.12.01
• 05.13.04
• 06.15.00

Step 1) – The first thing you are going to need to do is jailbreak your iPhone on the iOS 4.3.1 firmware using RedSn0w or the PwnageTool. If you have not done this please follow one of our guides: Jailbreaking with RedSn0w or Jailbreaking with the PwnageTool. If you are already jailbroken on the iOS 4.3.1 firmware please skip to step 2.

Step 2) - When you are jailbroken on the iOS 4.3.1 firmware please launch Cydia from your SpringBoard.

Step 2) - Now you are going to:

1. Tap on the “Manage” icon
2. Go into the “Sources” section

Step 3) – Once you are inside the “Sources” section you will need to:

1. Tap on the “Edit” button (top right hand corner of the screen)
2. Tap on the “Add” button (top left hand corner of the screen)

Step 4) - Once you click on the “Add” button a window should come up asking you to enter a Cydia/APT URL. Add the follow source listed below into the input field:

http://repo666.ultrasn0w.com

Once you add the source shown above please click the “Add Source” button. Cydia will now begin adding the source. Once Cydia has finished adding the source you will need to click the “Return to Cydia” button.

Step 5) - When you have successfully added the source you will need to go into the Search tab and search for “UltraSn0w 1.2.1″.

Step 6) - Once you find “UltraSn0w 1.2.1″ you will need to click the “Install” button.

When you have clicked the “Install” button please click “Confirm” and then wait till UltraSn0w is installed to your iPhone.

Note: You will need to restart your iPhone after installing UltraSn0w 1.2.1, and then your iPhone will reboot in an unlocked state. T-Mobile users in the USA also should also disable 3G mode in Settings->General->Network after installing UltraSn0w (while you do the first reboot).

Congratulations if this tutorial helped you unlock your iPhone 4/3GS on the iOS 4.3.1 firmware. Hopefully the Dev-Team will come up with an unlock solutions soon so users who are not on the required baseband versions will be able to unlock their iPhone. Let us know if you have any questions or comments in the comments section below…