UltraSn0w 1.2.5 was recently released to unlock the iPhone 4 running the iOS 5.0.1 firmware on the 01.59.00. baseband. It is important to keep in mind that in this new version of UltraSn0w you cannot unlock the iPhone 4 on any new basebands besides the *01.59.00 baseband.
*In order to see if you have baseband 01.59.00 on your iPhone 4 you will need to go into the Settings.app > General > About and look for the Modem Firmware field.
In this how to guide from iJailbreak.com you will learn how to unlock your iPhone 4 on the 01.59.00 baseband running the iOS 5.0.1 firmware. If you have an iPhone 3GS please click here to follow our guide specific to unlock the iPhone 3GS on a number of different basebands including the special 06.15.00 iPad baseband.
Note: In order to update to the official iOS 5.0.1 firmware and still preserve your baseband so it is unlockable, you will need to follow our in-depth how to guide by clicking here (simply select iOS 5.0.1 instead of iOS 5.0 as said in the how to guide). DO NOT under any circumstance update to the stock iOS 5.0.1 or you will update your baseband in the process. You will need to create a custom IPSW through RedSn0w or Sn0wBreeze (click here for more info).
Unlock iPhone 4 With UltraSn0w 1.2.5 On iOS 5.0.1
Step 1: You must already be running the iOS 5.0.1 firmware on your iPhone 4 (click here if you are not), and you must also be Jailbroken on the iOS 5.0.1 firmware. If your iPhone 4 is not Jailbroken please click here.
Step 2: After your iPhone 4 is running the iOS 5.0.1 firmware and is Jailbroken you will need to simply launch Cydia from your SpringBoard.
Step 3: Once Cydia is up and running you will need to go into the Sources page. To go into the Sources page tap Manage followed by Sources.
Step 4: Typically, the UltraSn0w repo is included with Cydia. If not, tap the Edit button followed by the Add button and you will be prompted to add a URL source. Type:
Followed by tapping the Add Source button.
Step 5: Cydia will automatically refresh and update sources.
Step 6: After Cydia is done refreshing sources. Tap the Search tab on the bottom tab bar and search for UltraSn0w. Once UltraSn0w appears, tap on it and you should see version 1.2.5. Read through the description and tap the install button to install UltraSn0w 1.2.5 to your iPhone 4 running the iOS 5.0.1 firmware.
Note: In case you are not familiar with UltraSn0w, it is a software unlock for your iPhone 4 meaning you can use your iPhone 4 with any carrier by simply inserting the SIM card.
Step 7: When UltraSn0w is installed you must restart your iPhone 4 and run RedSn0w to boot tethered, you’re done!
With UltraSn0w now installed on your iPhone 4 you will be able to enjoy the benefits of using any carrier while running the new iOS 5.0.1 firmware. Let us know if you have any questions in the comment section below…