iPhone users can now follow simple steps listed below to unlock iPhone 3G/3GS with iPhone OS 3.1.2 firmware using ultrasn0w after jailbreaking iPhone OS 3.1.2 using PwnageTool. Below guide holds good only for iPhone 3G and iPhone 3GS with baseband version 04.26.08. iPhone 2G users can follow our step by step guide on How to Unlock/Jailbreak iPhone 2G with iPhone OS 3.1.2. Users who have upgraded directly to iPhone 3.1.2 firmware from iTunes cannot unlock at present. iPhone Dev Team has also posted an Advisory to all iPhone users –
“iPhone users who need the unlock to understand they can keep it only by starting at 3.0 (or earlier) and updating solely to custom IPSWs that don’t update the baseband. For those who have been onboard the “unlock train”, simply install ultrasn0w via Cydia once you’ve restored to your custom IPSW. Don’t forget to turn off the “3G” setting in Settings->General->Network if you use T-Mobile in the U.S.A.”
Ultrasn0w tool to unlock iPhone 3G and iPhone 3GS 3.1.2 will work only if your iPhone is jail-broken. You can jailbreak your iPhone 3G/3GS using PwnageTool 3.1.4
Guide to unlock iPhone 3G/3GS with iPhone OS 3.1.2 firmware
Step -01- Launch ‘Cydia Installer’ from your SpringBoard and click Manage tab at the bottom of your iPhone screen.
Step -02- Navigate to Sources -> Edit and then click Add (at the top left of the screen)
Step -03- Enter URL http://repo666.ultrasn0w.com/ and press the Add Source button.
Step -04- Now, Simply click the install button at the top right of the screen to install Ultrasn0w.
Step -05- Once the Ultrasn0w installation is completed successfully; reboot (Power Off and then Power On your iPhone).
Important Note – T-Mobile users must disable 3G before installing and using ultrasn0w to unlock iPhone 3G.