How to upgrade iPhone 3G/3Gs to 06.15.00 baseband using Redsn0w
As we announced yesterday, you can now unlock on firmware 4.2.1 on iPhone 3G and 3Gs, please notice that this is not for iPhone4, updating your baseband to 06.15.00 on your iPhone4 would be pointless so please don't do it. There are certain risks involved with updating your baseband to 06.15.00. You may void any warranty due to baseband upgrade or miss critical upgrades for your baseband as they are released by Apple. There is no way to hide your baseband . After the upgrade , you cannot restore an earlier baseband by any means.
Step-by-Step Guide to Upgrade Baseband 06.15.00 :
1. Download iOS 4.2.1 .ipsw files for your iphone 3GS 3G
2. Download and install latest version of iTunes 10.1 on your computer . Update your device to iOS 4.2.1 downloaded in Step 1
3. Download RedSn0w 0.9.6b5 from the links above.
4. Now launch RedSnow 0.9.6b5 and browse the ios 4.2.1 .ipsw file you just downloaded.
5. Next step is where RedSn0w identifies the .ipsw and prepares for jailbreaking your device.
6. Now you will be shown the screen where you have to make choices . Select “Install Cydia” & “Install Ipad Baseband”
7. Next you must connect your device to the computer. Make sure its turned off before you click on Next .
8. Now you must enter DFU mode. [ How-to enter DFU Mode ]. Follow on-screen instructions to put your device in the DFU mode by holding the Home and Power button together for 10 seconds. Release the Power button while still holding the Home button .
9. Now RedSn0w will start jailbreaking your phone and when it's done you will be on the 06.15.00 iPad baseband.