How: Unlock iPhone 4 Baseband 4.12.01 And iPhone 4S Baseband 2.0.10 on iOS 5.1

Two days ago Apple released iOS 5.1 firmware to the public for iPhone, iPad and iPod touch. iPhone Dev-team have already advised jailbreakers and unlocker to stay away from this update to keep their iOS 5.0.1 untethered jailbreak safe. iPhone 4Sand iPad 2 jailbreak users should stay away from iOS 5.1 firmware because you won't be able to downgrade your iDevice iOS firmware from iOS 5.1 to 5.0.1 or 5.0 even if you have your SHSH blobs saved because Apple has stop signing older firmwares on these iDevices.
Now the bad news is just like iOS 5.0 firmware update this iOS 5.1 firmware update has also brings baseband update for iPhone 4 and iPhone 4S. If once your iPhone 4or iPhone 4S updated to iOS 5.1 firmware then it will change your device baseband and the new baseband for iPhone 4 will be 4.12.01 and iPhone 4S' baseband will be 2.0.10. Unfortunately, for the time being there is no hardware or software unlocksolution available for both baseband.

Unlock iPhone 4 Baseband 4.12.01 And iphone 4S Baseband 2.0.10 On iOS 5.1Firmware

Many users have updated their iPhone 4/4S iOS firmware to the latest iOS 5.1firmware without knowing the baseband up gradation and now they have lost theirunlock and jailbreak as well. Now you must have to wait until some hardware or software unlock solution release by iOS devs or hackers community. iPhone 4S users who have already unlocked their iPhones on baseband 1.0.11, 1.0.13 and 1.0.13 using Gevey SIM Ultra must stay away from iOS 5.1 firmware because there is no solution available for iOS 5.1′s baseband 2.0.10. In order to prevent your iPhone 4 oriPhone 4S updating to 4.12.01 and 2.0.10 baseband you should stay away from restoring iOS 5.1 firmware.

 

More: http://cydiaism.com/unlock-iphone-4-baseband-4-12-01-and-iphone-4s-baseband-2-0-10-on-ios-5-1-firmware/