In order to unlock the iPhone 3G and 3Gs stuck on 05.14 or 05.15 baseband, the iPhone DevTeam pulled a magic unicorn switcheroo out of their shiny top hats:
They took an exploit that was closed by Apple in the iPhone baseband, but still active in the iPad 3G baseband; they also tweaked redsn0w , and by using the latest release , basically you transfer the iPad’s baseband ( version 06.15.00 ) into your iPhone – baseband which can be unlocked.
WARNING — YOU DO THIS AT YOUR OWN RISK! PLEASE UNDERSTAND THE CONSEQUENCES OF UPDATING TO 06.15.
1.There is no way to come back down from 06.15, and there’s no hiding the baseband version from Apple. You’ll be voiding your warranty in a very obvious way.
2.If some future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).
3.Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail). You’ll need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).
Certainly don’t update to 06.15 if you don’t need to! Only do this if you need the unlock and you’re stuck on 05.14 or 05.15, and you’re willing to assume the above risks.
What you need:
iPhone 3G firmware 4.1
NOTE: We used one of our previous redsn0w tutorials, but we made the necessary adjustments. Don’t be thrown off by the fact that most of the screenshots say ‘redsn0w 0.9.6b1′
NOTE: If you do flash your baseband via redsn0w, please keep it plugged into USB the whole time. You don’t want your battery to die during the flash process!
1. Restore your device with a stock iOS 4.2.1 firmware. ( again, by doing this you will loose the ability to unlock!!!)
2. Run redsn0w, and click on browse. Browse for the stock iOS 4.2.1 and open it
3. Wait for redsn0w to recognize it and click ‘Next’
4. On the next screen select what you want to be installed on your iOS device(s). By default, Cydia and "enable battery percentage" is selected. I suggest you deselect battery percentage and everything else, and just install Cydia. This will improve ( a bit ) the overall speed of your device – if you are on a iPhone 3G. If you choose to “Enable battery percentage”, you actually toggle that off and on via Settings->General->Usage.
IF you only need to restore with a custom firmware, deselect everything, and select only 'Just enter pwned DFU mode right now'.
In this case, you will want to select, install iPad baseband. When you select it, you will get a warning that tells you the risk of this process.
5. redsn0w will ask you to turn your device off. If it’s not already off, plug it in FIRST and then turn it off. Click next to continue
6. Now, you will need to put your device in DFU mode. Follow the instructions on the screen.
7. Wait a few seconds for redsn0w to do its thing, and you are done. You can close redsn0w because everything else it’s happening directly on the device.
8. Now load Cydia, and install ultrasn0w 1.2
NOTE: Any Windows users seeing “Waiting for reboot” for too long (more than 20 seconds or so), please try “shaking” the JB process by unplugging then replugging your USB cable (while letting redsn0w continue to run). Also, try using a USB port “closer” to your computer (as opposed to on your monitor or behind another hub).
Tethered boot how to:
If you have a tethered jailbreak, and your iPhone needs to reboot, you will need to use redsn0w to reboot it. Let’s take a look at how to do it:
1. Open redsn0w 0.9.6.b4 and click on browse. Look for iOS 4.2.1 that you saved on your desktop and select it…
2. Now, select ‘Just boot tethered right now’ and click next…
3. Follow the directions on the screen to put your iOS device in DFU mode…
4. That’s it.