How-to Permanently Unlock Baseband 05.16.07 of the iPhone 3GS with iOS 6

If your iPhone is locked to AT&T, you can immediately go ahead to this page: Factory Unlock AT&T iPhone 4S, iPhone 4, iPhone 3GS and by simple submit your IMEI number you can get your iPhone 3GS unlocked the next day. Yes, unlocking baseband 05.16.07 is supported, including baseband 05.16.05, 05.16.02, 05.16.01 since it will factory unlock your iPhone3GS, all baseband versions will be supported.

Now, here is the hardest part, if you dont really want to pay the service to factory unlock your iPhone 3GS with baseband 05.16.07, now let’s go with the painful process to unlock iPhone 3GS 05.16.07.

DO IT AT YOUR OWN RISK!!!

The rule before install or downgrade iPad baseband (you should stop if you are not eligible), Serial number should NOT bexx134 or later (you can check it on Settings → General → About, because the iPad baseband is not compatible with 3GS units manufactured week 34 of 2011 or later. If your serial number shows xx134 or later and you still want to continue, youriPhone 3GS will be dead for sure.

Get every thing prepared. These are things you need to download.

1. iOS 4.1 IPSW firmware for iPhone 3GS. Why do you need iOS 4.1 IPSW? Here is a bit explanation: Apple stills signs iOS 4.1 (means that you’re still allowed to downgrade to iOS 4.1 without SHSH Blobs). Once you have iOS 4.1 installed on your 3GS, you must install iPad baseband 06.15.00, and after that you can downgrade 06.15.00 to 05.13.04.
2. Download redsn0w 0.9.14b1
3. Download TinyUmbrella latest version from http://thefirmwareumbrella.blogspot.com/
4. Download iTunes 10.4.1: Windows (32-bit) / Windows (64-bit) / Mac OS

Part II: Let’s start downgrading

You will need to remove your current iTunes and install the older version of iTunes (10.4.1) you have downloaded earlier.

1. Once done, open iTunes.
2. Put iPhone 3GS into DFU mode, and connect the iPhone into the computer. iTunes will say your iPhone is in recovery mode, click OK.
3. From iTunes summary page, HOLD DOWN SHIFT button (on Windows) or OPTION button (on Mac) and click Restore.
4. Browse iOS 4.1 IPSW file you have downloaded and click Open. It will takes few minutes to restore, just sit and relax and wait until the process complete.
   SenseiPhone.com confirmed that iOS 4.1 signing is wide open, BUT only for 3GS. So you can downgrade iPhone 3GS with any iOS version to iOS 4.1. We don’t know why iOS 4.1 is still signed and not iOS 4.2.1 nor iOS 4.3.3.
   Might be accidental or it has some other purpose that is unknown so far. But it works for iPhone 3GS only.
   In short: YES YOU CAN DOWNGRADE WITHOUT SHSH BLOBS to iOS 4.1 only (3GS only)

If you get iTunes unknown error 3194, remove gs.apple.com line from the hosts file.
If you get iTunes unknown error 1015, exit the recovery look with redsn0w “Recovery Fix” option.

Recovery Fix Option on redsn0w

Part III: Install the iPad baseband (baseband 06.15.00) to your 3GS

REMEMBER: The rule before install or downgrade iPad baseband (you should stop if you are not eligible), Serial numbershould NOT be xx134 or later, you can check it on Settings → General → About.

1. Open redsn0w 0.9.14b1. Click Extras → Select IPSW → Browse and Select iOS 4.1 IPSW you downloaded earlier.
2. Click the Back button to go back to redsn0w’s main menu and click Jailbreak. Follow the instructions til you get here, where you can select options. Select Install iPad baseband and install Cydia options.
   

   Install iPad baseband
3. Follow the on-screen instructions, once the process complete, your iPhone 3GS will have jailbroken iOS 4.1 with modem version (a.k.a baseband) 06.15.00 installed as you can see on Settings → General → About.

The last part: Downgrade baseband 06.15.00 to 05.13.04

• Read here: How-to Downgrade Baseband 06.15.00 to 05.13.04. Make sure to select iOS 4.1 IPSW instead of iOS 5.1.1 shown on the tutorial.
• The step is actually the same as Part III, except you need to select “Downgrade from iPad baseband” instead of “Install iPad baseband“.
  
• Once the process done, you will have baseband 05.13.04 on the iPhone, which can be unlocked with ultrasn0w. How-to Unlock iPhone with Ultrasn0w

That’s all you need to do in order to unlock baseband 05.16.07 iOS 6, by upgrading and downgrading the baseband.

If this process is too complicated for you, we suggest you to Factory Unlock your iPhone instead. Check the full list of supported carriers here: http://senseiphone.com/factory-unlock-service/.