iPodXS

A special edition of PwnageTool (version 4.1.3) has been released which can update the baseband of iPhone 3GS & 3G to 06.15.00 so that they can be unlocked using Ultrasn0w 1.2 on the latest iOS 4.2.1 or iOS 4.1 firmware. This is important because basebands 05.14.xx and 05.15.xx are currently not unlockable using Ultrasn0w.

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. 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).

2. Starting with iOS 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).

Follow the instructions posted below to update your iPhone 3GS or 3G to 06.15.00 baseband and jailbreak it on iOS 4.1 /4.2.1.

1) Download iPad 3.2.2 firmware file from the download page (Required for 06.15.00 baseband).
2) Download the required iOS 4.2.1 or iOS 4.1 firmware file (See download section).
3) Download PwnageTool 4.1.3 from here.
4) Start PwnageTool 4.1.3 and point it to iOS 4.2.1 / 4.1 firmware file.
5) You will now be prompted to update your baseband to 06.15.00 so that it can be unlocked using Ultrasn0w 1.2.
6) Now point PwnageTool 4.1.3 to iOS 3.2.2 for iPad. PwnageTool will now fetch the exploitable 06.15.00 baseband from 3.2.2 firmware and will replace the baseband in iOS 4.2.1 / 4.1.
7) Click the next arrow now to allow PwnageTool to create this custom ipsw file for you.
8) Now follow the following steps to enter DFU mode:

Hold Power and Home buttons for 10 seconds
Now release the Power button but continue holding the Home button for 10 more seconds
You device should now be in DFU mode

9) You will now have to restore your iPhone to this custom firmware 4.2.1 / 4.1 file. Start iTunes, click on your device icon from the sidebar in iTunes. Now press and hold left “alt” button (“Shift” button on Windows) on the keyboard and then click on “Restore” (Not “Update” or “Check for Update”) button in the iTunes and then release the “Shift” button.

This will make iTunes prompt you to select the location for your custom firmware 4.2.1 / 4.1 file. Select the required custom .ipsw file and click on “Open”.

10) Now sit back and enjoy as iTunes does the rest for you. This will involve a series of automated steps. Be patient at this stage and don’t do anything silly. Just wait while iTunes installs the new firmware 4.2.1 / 4.1 on your iPhone 3GS or 3G. Your iOS device screen at this point will be showing a progress bar indicating installation progress. After the installation is done, your iPhone will restart automatically and you should now have a fully jailbroken iPhone 3GS or 3G with 06.15.00 baseband.

UPDATE 1 A new fixed version of PwnageTool bundle (download here) for iPhone 3GS on iOS 4.1 has been released. Here’s how to use it:
a)Copy PwnageTool that you downloaded in Step 3 to a folder on your desktop. Right click, and then click on “Show Package Contents” as shown in the screenshot below.

b) Navigate to Contents/Resources/FirmwareBundles/ and copy-paste this iPhone2,1_4.1_8B117.bundle file in this location and then simply close this folder. Now follow Step 4 and onwards as posted in the guide above.

UPDATE 2

PwnageTool Bundle for iPhone 3GS (old bootrom) on iOS 4.2.1 is now available (download link)
For those Mac users with an old-bootrom 3GS who really know what they’re doing, here’s a minimal 3GS 4.2.1 bundle that will get you to 4.2.1 without updating your baseband.  Be sure to uncheck “Activate the iPhone” using Expert mode.  To actually jailbreak after you’ve restored with the help of that bundle, please use redsn0w.

Redsn0w 0.9.6b5 has just been released which can jailbreak and update iPhone 3GS & 3G baseband to 06.15.00 so that it can be unlocked using the newly released Ultrasn0w 1.2.
The new redsn0w 0.9.6beta5 is out.  It gives both Windows and OSX users the ability to flash the iPad 06.15 baseband on iPhone3G or iPhone3GS.  It fetches the baseband files directly from Apple for now (the only IPSW you ever point it at is the stock IPSW for the FW on your iPhone right now).  There may be a long delay while it’s doing this (their servers are getting pounded right now)
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!

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. 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).

2. Starting with iOS 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).

Follow the instructions posted below to update your iPhone 3GS or 3G to 06.15.00 baseband and jailbreak it on iOS 4.1 /4.2.1.

1) Download iOS 4.2.1 for iPhone 3GS or 3G.
2) Update/Restore to iOS 4.2.1 firmware using the IPSW file you just downloaded via iTunes 10.1.
3) Start Redsn0w 0.9.6b5 and point it to iOS 4.2.1 firmware to proceed with the jailbreak.
4) Now select “Install Cydia” & “Install iPad baseband” options and then click “Next” to continue. Redsn0w will now fetch the exploitable 06.15.00 baseband from 3.2.2 firmware and will replace it the baseband in iOS 4.2.1 / 4.1.

Note: Install iPad baseband option is applicable to iPhone 3GS & 3G users only who rely on a carrier unlock.

5) Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.

At this stage you will be presented with a screen where you will have to quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.

Step 6: Sit back and enjoy while Redsn0w will do all the rest for you. Once done, your iPhone or iPod touch will restart automatically and you will find it jailbroken on the latest iOS 4.2.1 firmware, with the unlockable 06.15.00 baseband.

For iPhone 4, 3GS (New Bootrom), iPod touch 4G / 3G / 2G, iPad ONLY:
7) Now from here onwards, whenever you want to do anything related to jailbreak like SSHing into your device, or running Cydia, you must first run your device in the so called “jailbroken state” on every reboot by using “Just boot tethered right now” option in Redsn0w.

Download Redsn0w 0.9.6b5 for Windows
Download Redsn0w 0.9.6b5 for Mac