Earlier Today Apple released the final version of iOS 5 for iPhone, iPod Touch and iPad. iPhone Dev Team in return also active in chasing the game, released new version of Redsn0w which has got a new feature called “Custom IPSW“. This option in Redsn0w will allow users to create custom Firmwares iPSW and will be able to preserve their baseband so they can unlock their iPhone via Ultrasn0w or Gevey sim.
iPhone Dev Team Explains:
The new “Custom IPSW” button on the Extras screen will create a custom IPSW without the baseband update for 4.3.3 or 5.0gm (iPhone3GS and iPhone4 only, for now). Remember to NOT accidentally restore to the stock IPSW after you create the custom one! The custom one begins with NO_BB_ (for “no baseband”). On Mac iTunes, you select an IPSW by holding down the Option key while clicking “Restore”.
You must enter “Pwned DFU” mode before trying to use the NO_BB_ IPSW with iTunes (and your hosts file cannot be pointing to Cydia’s servers due to the new blob nonce mechanism they’re using in iOS5).
Download Redsn0w 0.9.9b5 or Windows (coming soon)
Download iOS 5 For your iPhone 4 or 3GS
How To: Create And Install Custom Firmware iOS 5 on iPhone 4, 3GS With Baseband Preserved Using Redsn0w 0.9.9b5:
Step 1: Open Redsn0w which you downloaded earlier and click Extras.
Step 2: Now Click Custon IPSW and browse for the iOS 5 you already downloaded. Remember Redsnn0w will create the custom IPSW firmware in the same folder where iOS 5 is download with a name NO_BB_ IPSW.
Step 3: Once Redsn0w finishes creating Custom iOS 5. You have to prepare your iPhone for custom iPSW installation. All you need is to open Redsn0w again and go to Extras and click Pwned DFU mode which will put your iPhone in DFU mode. Once in DFU mode, Open iTunes and go to your iPhone tab. Instead of hitting “Restore” in iTunes hold down shift(win) or option(mac) and then hit restore. A dialog window will open up again asking you to select your firmware. At this point select the CUSTOM iOS5 firmware you created. It is extremely important that you select the correct firmware. The custom firmware will begin with “NO_BB”
Once iTunes done with installing the custom firmware on your iPhone. Your new iOS 5 will be installed on your iPhone with older baseband which will allow you to unlock it with ultrasn0w or Gevey Sim. Ultrasn0w is not yet updated for iOS 5 but iPhone dev team confirmed that it will be updated today anytime.
You can tethered Jailbreak your iPhone 4 or 3GS on iOS 5 Following this Guide.