We’ve some great news for users who want to unlock their iPhone.

Hacker Loktar_Sun from weiphone.com has managed to successfully unlock iPhone 4S using SAM (Subscriber Artificial Module) – a jailbreak tweak that until now allowed users to hacktivate their iPhones.

Update: 

SAM has been updated by Sam Bingner, which makes it a lot easier to unlock your iPhone. Check this post for the step-by-step instructions to unlock your iPhone using the latest version of SAM.

Things that you need to unlock your iPhone using SAM:

• You need a jailbroken iPhone. If you haven’t done it yet then check out our How to Jailbreak webpage for links to the latest tutorial to jailbreak your iPhone.
• Latest version of iTunes and (of course) an internet connection.

Important Points: 

• Your phone will work normally with your SIM card and that SIM card ONLY since we have tricked iTunes to think that ICCID is one of the intended carrier’s. The phone can be rebooted and connected to iTunes freely without losing the “unlock”, at least for now. 
• Due to the above limitation, if you have an off-contract AT&T iPhone then we would still recommend requesting AT&T to unlock your iPhone.
• This method should work with iPhone 4S, iPhone 4 and iPhone 3GS.
• This method has been tested on a jailbroken iPhone on iOS 5.0.1, but should work even on tethered iOS 5.1.
• This method should work across all basebands.
• You don’t need the original SIM, you just need to know what carrier it was for (to create an official looking IMSI). 
• If you’ve hactivated your iPhone, you must first unhactivate it (just use SAM’s “stockify” option when it notices you’re hacktivated).

Please find the step by step instructions to unlock your iPhone:

Step 1: Launch Cydia on your jailbroken iPhone.

Step 2: Sam Bingner’s SAM (Subscriber Artificial Module) package.

• Tap on the Manage tab
• Then tap on Sources
• Then the Edit button
• Enter repo.bingner.com as the Cydia/Apt URL
• Tap on Add Source

Cydia will verify the URL of the repo and successfully install it.

Step 3: After the package is installed, you need to Install SAM and SAMPrefs.

• Either tap on Changes tab or use the Search tab to search for SAM
• Select SAM for the list of search results
• Tap on the Install button
• Then tap on the Confirm button.
• Tap on the Reload Springboard button when prompted.
• This will also install SAMPrefs

Once you have SAM installed, you need to follow the instructions mentioned below, which was published by Laforet based on instructions provided by Loktar_Sun over at weiphone.com:

Step 4: Enter SAM by either going through the settings menu or find the SAMPrefs icon on your springboard. You will need to have the SIM card you intend to use in your phone.

Step 5: Go to utilities and select “De-Activate iPhone”, your ActivationState under “More Information” should now be “Unactivated”

Step 6: With SAM enabled, choose “By Country and Carrier” in “Method”; find your carrier, for some carriers operating more than one Carrier ID you may need to select “SIM ID”; easy to tell since iTunes will not activate if the wrong IMSI is selected. Update: Some readers have managed to successfully unlock their iPhone using the Auto Detect method. Thanks everyone for your feedback.

Step 7: Go to More Information”, copy or write down the IMSI in “SAM Details”, then tap “Spoof Real SIM to SAM”.

Step 8: Go back to the main SAM screen and change your “Method” to manual. Paste or enter the IMSI string we saved in Step 7.

Step 9: Connect your iPhone to your computer and allow iTunes to do its job (namely re-activating your phone), double click “Phone Number” parameter at the main device screen and make sure that the ICCID matches that of your SIM card. If not you need to start over from Step 1.

Step 10: Unplug your phone, close iTunes.

Step 11: Disable SAM. The source article says to uninstall SAM and delete your lockdownd folders; it’s unnecessary.

Step 12: Connect your phone to iTunes again, you should get an error saying that your phone cannot be activated. This is normal. Just close iTunes and open it again.

Step 13: You should see signal bars in a short time, congratulations.

Step 14: Push notifications may stop working after this procedure but can be easily restored with “clear push” utility in SAM followed by connecting to iTunes.

Video Tutorial:

If you’ve problems following the step-by-step guide then check out the video tutorial by Jeff Benjamin embedded below:

MuscleNerd of the iPhone Dev team has confirmed that he has managed to successfully unlock his iPhone 4S and got it to work on T-Mobile USA’s network using this method.

After you’ve successfully unlocked your iPhone, follow these step-by-step instructions to take a backup of the activation ticket created using this SAM unlocking trick as it will be useful in the future.

So let us know how it goes.

Update 1:

Post updated with some useful information provided by the ever so dependable MuscleNerd.

Update 2:

Post updated with link to step-by-step guide to take a backup of the activation ticket  created using this SAM unlocking trick.

Update 3:

If you were not able to unlock your iPhone, then please note that SAM has just been updated by Sam Bingner, which makes it a lot easier to unlock your iPhone. Check this post for the step-by-step instructions to unlock your iPhone using the latest version of SAM.

Update 4:

Apple has started blocking SAM trick to unlock iPhone, check out this post for more details.