redsn0w jailbreaking tool along with an updated version of Ultrasn0w that supports the existing iPhone unlocks on iOS 5.1.1. If you are an iPhone user who relies in ultrasn0w unlock, you can safely update your iPhone to iOS 5.1.1 by preserving the baseband using redsn0w or sn0wbreeze and then install ultrasn0w 1.2.7 unlock to unlock your iPhone.
This updated ultrasn0w unlock works on for the supported basebands and does not include any other iPhones. This update is just to support iOS 5.1.1 firmware unlock and should not be considered as a new unlock for non unlock-able basebands.
Steps To Unlock iPhone Using Ultrasn0w 1.2.7
Step 1 : Jailbreak your device
Step 2 : Launch Cydia
Step 3 : Search for Ultrasn0w and install it.
Step 4 : If you are unable to see ultrasn0w in search output go to manage
Step 5 : Sources and add the following repo http://repo666.ultrasn0w.com
Step 6 : Now go to search and type ultrasn0w and should be able to see it.
Step 7 : Download and install ultrasn0w to unlock your iPhone.