[Tutorial] Unlock iPhone on iOS 4.3.2 with Ultrasn0w 1.2.2

In addition to PwnageTool 4.3.2, iPhone Dev Team has released the Ultrasn0w 1.2.2 for making it compatible with the most recent iOS 4.3.2 firmware. Instead of ultrasn0w fixer, you may now use official ultrasn0w for unlocking your device on iOS 4.3.2 running old baseband.
Ultrasn0w 1.2.2 – Which Baseband are Supported?

The official ultrasn0w 1.2.2 will only support iPhone 4 baseband 01.59.00, iPhone 3GS basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04 including 06.15.00. BB 05.14.02 and 05.15.04 are still locked and you must update your iPhone 3GS to baseband 06.15.00 and then run ultrasn0w 1.2.2 to unlock it. This method restricts you to use GPS, and if you think GPS is not a sure stopper for you then you are good to go. The tool does not unlocks iPhone 
4 baseband 2.10.01, 3.10.01, 4.10.01.

Steps to unlock iPhone 4 or iPhone 3GS on old Baseband

Step 1: Use PwnageTool 4.3.2 to jailbreak your iPhone 4 or iPhone 3GS (Both Old and New Bootrom) on firmware iOS 4.3.2.(Mac Only). Windows user can use sn0wbreeze 2.6 for jailbreaking their device.

Step 2: Start Cydia on your jailbroken iPhone iOS 4.3.2 springboard.

Step 3: Select Manage tab at the bottom of your iPhone screen and then select Sources.

Step 4: Select Edit and then select Add. Now enter a URL source. Type repo666.ultrasn0w.com and select on Add Source. Once Cydia has added the source click onReturn to Cydia button.

Step 5: Once the installation is completed. Search for ultrasn0w in Cydia and install it.
Step 6: This will automatically unlock your jailbroken iPhone 4, iPhone 3GS.

Step 7: After running ultrasn0w 1.2.2, please reboot your iPhone using the normal “slide to power off” swipe.  T-Mobile users in the USA must disable 3G mode in Settings->General->Network. That’s it!