Today we have good news for all those users whose iPhone rely on a Carrier Unlock via UltraSn0w. The Dev-Team has released a newer version of UltraSn0w 1.2.4 to unlock iPhone 4 or iPhone 3GS on iOS 5 old baseband. Unfortunately, this update doesn’t add support for any new basebands, but users on older basebands can unlock their iPhone on iOS 5 using this version.

According to the Dev-Team:

We’ve updated ultrasn0w to be compatible with iOS5, which came out a few days ago.  While ultrasn0w 1.2.4 (available now in Cydia) doesn’t add support for any new basebands, the update is required for any ultrasn0w unlockers trying out iOS5 (it remains backwards compatible though, so you should be able to use it no matter what firmware you have).

This version of UltraSn0w supports basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04, and 06.15.00 for iPhone 3GS while the baseband supported for the iPhone 4 is 01.59.00. All you need to do is jailbreak your iPhone on iOS 5 while preserving basebands. You can follow our step-by-step guide to jailbreak iPhone 4, iPhone 3GS on iOS 5. One thing should be kept in mind that this is a tethered jailbreak.

There is also a special Note for users who have a iPhone 3GS and iPad baseband 06.15.00, which is:

Note: there’s a special “trick” that iPhone3GS owners with baseband 06.15 need for iOS5.  During the new setup screens you see when you start iOS5 for the first time, you’ll be asked about Location Services.  Be sure to select “Disable Location Services” when asked!  Later on in the setup, you’ll have the chance to turn on Location Services again when asked if you want to use “Find my iPhone”.  It’s fine to turn it back on at that point, if that’s your desire (or you can always go in and enable it in Settings.app).

Also, some iPhone3GS users with the 06.15 baseband may have tried to install iOS5 using a stock IPSW (even though you should never ever try to use a stock IPSW if you’re an ultrasn0w unlocker).  If you did try this, your baseband is probably in an inconsistent state, and you’ll need to reflash the 06.15 baseband again (using redsn0w).  Be very careful if you use redsn0w to reflash the iPad baseband — don’t interrupt the process! And please avoid using stock IPSWs in the future  Unlockers should never go near stock IPSWs

Let us know if UltraSn0w 1.2.4 worked for you in the comments below…