This is a tutorial on how to unlock iPhone 4 iOS 5.1.1 with Sn0wbreeze custom firmware. That method also works with iPhone 3GS. If your iPhone is unlockable with ultrasn0w or Gevey (which is slightly worse) then continue reading to unlock your iPhone 4. If your iPhone is not factory unlocked you probably know the routine very well but if you are new to custom firmware without baseband update and unlock it is better for you to understand what you are doing.

Why do you need custom firmware:

• It allows you to restore your iPhone without baseband update.
• Once preserved, your baseband can be unlocked with previous methods (aka ultrasn0w/Gevey SIM or else).
• Remember that there is no software method of downgrading baseband version back to unlockable.

Things you need to unlock iPhone 4 iOS 5.1.1

• iPhone 4 on baseband 01.59.00 (can be handled with ultrasn0w), 02.10.4, 03.10.01 and 04.10.01 (handled with Gevey SIM)
• iPhone 3GS with baseband 05.11.07, 05.12.01, 05.13.04 or iPad baseband 06.15.00
• Latest Sn0wbreeze 2.9.5 (download)
• Ultrasn0w Fixer iOS 5.1.1
• Ultrasn0w 1.2.5

Step One: Backup your iPhone with iTunes, iCloud or in any other convenient way. Step Two: Use this sn0wbreeze tutorial (steps 1-10) to upload custom firmware and jailbreak your iPhone. Don't mind the older version there, the steps are the same. If you have error 3194 while updating - here's the fix, error 1015 fix is here. Step Three: Use this guide to unlock with ultrasn0w 1.2.5.

How to unlock iPhone 4 iOS 5.1.1 with Gevey SIM:

Step One: Take off your SIM card from the SIM tray and reboot. Step Two: Once SpringBoard is loaded, turn off 3G and cellular data. Insert Gevey SIM interposer together with your SIM. Step Three: Once Accept Screen shows up - tap 'Accept'. Step Four: No Service sign will appear instead of signal bar. Wait for 15 secs and dial 112. Don't wait until you get connected, just hnag up in 1-2 secs. Step Five: Turn on Airplane Mode and wait until ‘NO SIM CARD INSTALLED’ message appears. Switch off the airplane mode and tap OK when SIM FAILURE appears. You'll see a full signal bar indicated that you're now connected to your cell network. Congratulations! Now your iPhone 4 is unlocked on iOS 5.1.1 with untethered jailbreak! Thanks to guys from beijingiphonerepair for the tutorial. Have any questions? Like this article? Let us know in the comments below and share it with your friends.