iPhone Dev Team has released the eagerly awaited unlock for iPhone 3G and iPhone 3GS users on iOS 4.2.1 just as they had promised.

Apple had patched the exploit that allowed users to unlock their iPhone in iOS 4.1 released on September 8 so it has been a long wait for users who wanted to software unlock their iPhone to use it with any carrier.

Dev Team has provided the following information on their blog about the free software unlock:

Today we’re pleased to announce our free carrier unlock for iPhone3G/3GS owners with a baseband later than 05.13.04.  The unlock for that baseband exploited the AT+XAPP command, thanks to a crash initially discovered by @sherif_hashim (@Oranav also found this crash).  So what hole are we exploiting today, since Apple closed that AT+XAPP hole?  Well, we’re exploiting the exact same hole!

It turns out that the very first iPad firmware 3.2.2 has baseband version 06.15.00 still vulnerable to AT+XAPP.  The iPad baseband is built for the exact same baseband chip as the iPhone3G/3GS — they’re fully compatible! Some of us have been running 06.15 for weeks now on our iPhones in preparation for this release.

Since 06.15 is a higher version than 05.14 or 05.15 (where AT+XAPP is gone), anyone stuck at those versions can simply upgrade to 06.15 to unlock again!  Luckily for us, Apple *still* provides the iPad FW 3.2.2 with this vulnerable baseband right from their own servers. (Grab it now, before they take it down!)

We’ve been busy updating both PwnageTool and redsn0w to make the baseband update as seamless as possible.

1. First up is “PwnageTool 4.1.3 Unlock Edition”.  It has a special dialog box which will ask you if you want to update to the iPad baseband.  You must already have the iPad 3.2.2 IPSW on your computer (see the above link)….so just point PwnageTool at it (or let it find it on its own if you’re in “simple” mode).
2. Directly after PwnageTool 4.1.3 is available, the official ultrasn0w repo http://repo666.ultrasn0w.com will be updated with ultrasn0w 1.2, which covers iPhone 4 baseband 01.59.00 and iPhone 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04 and now 06.15.00.
3. Finally, we’ll release an update to redsn0w today for those without Macs and can’t run PwnageTool.  The new redsn0w will give you the option to update your baseband to 06.15 too.

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.

This PwnageTool also contains a 4.2.1 bundle for iPhone3G owners…for all else, it’s still only 4.1.  If you have an iPhone3GS with an old bootrom, the new redsn0w will handle 4.2.1 for you (in fact it covers 4.2.1 for all devices, even though some of them are still tethered at 4.2.1 until @comex can work some untethering magic).  iPhone3GS users with old bootroms who want to go to 4.2.1 should not use this PwnageTool! Update to stock 4.2.1 first, then use the upcoming redsn0w to update your baseband.

Update 1:

Dev Team has released the following update:

There’s an error in the bundle for the iPhone3GS 4.1 that prevents the new baseband from being used.  If you know your way around OSX, please download the fixed bundle, and unzip it if Safari hasn’t already done so.  Then “Show Package Contents” of PwnageTool.app, navigate to Contents->Resources->FirmwareBundles and drop it there.   Otherwise, please wait for the updated PwnageTool, or the OSX version of redsn0w coming soon.

Update 2:

Dev Team has released Redsn0w 0.9.6beta5 For iOS 4.2.1 Released To Unlock iPhone 3GS & iPhone 3G

Update 3:

iPhone Dev Team Releases Unofficial PwnageTool Bundle For iPhone 3GS

Update 4:

Activate iPhone Without Official Carrier SIM And Also Fix Poor Battery Life Issue After Unlocking Using SAM

Update 5:

Unlocking iPhone After Updating Baseband To 06.15.00 Causing GPS Issues

Please remember that unlocking your iPhone may void its warranty so proceed with caution.

As always, let us know how it goes.