How to jailbreak and unlock iPhone 4 / 3GS on 5.1 with Ultrasn0w fixer

How to Unlock iPhone 4 5.1 with Ultrasn0w Fixer

STEP 1: Create custom iOS 5.1 ipsw firmware

Step 1a: Connect your iDevice with your PC via USB and open Redns0w you just downloaded above (link).

Step 1b: Start Redsn0w, press on “Extras” > “Custom IPSW” and then point Redns0w to iOS 5.1 ipsw firmware that you downloaded above.

Now Redsn0w will start cooking your custom iOS 5 ipsw firmware

Step 1c: Click on “Pwned DFU”

Step 1d: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.

At this stage you will be presented with a screen where you will be guided on how to enter DFU mode. Quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.

Step 1e: Open iTunes then Restore your iPhone 4, 3GS to the Custom iOS 5.1 ipsw (the file name begins with NO_BB).

Step 2: Now Open Cydia > Manage > Sources > Edit >
Add then write the following repo :
.
http://repo.iparelhos.com
.
Step 3: After installing this repo, tab on search and search for “Fix Ultrasn0w for iOS 5.1“ then install it.

GD P.S.: now you have unlocked iPhone 4, 3GS on 5.0.1 using Fix Ultrasn0w for iOS 5.1

 
Fix Ultrasn0w for iOS 5.1 support the below basebands :
01.59.00
04.26.08
05.11.07
05.12.01
05.13.04
06.15.00