Unlock for iPhone 4 iPhone 4S running iOS 5.0 , 5.0.1 , 5.1 running modem baseband 04.11.08 , 04.12.01 and older is now possible using SAM or Subscriber Artificial Module .
A Chinese hacker named Loktar_Sun has manipulating SAM (Subscriber Artificial Module) package.
Steps To Unlock:
First you will need to add the following source to Cydia to download the SAM package from Manage > Sourses > Edit > Add, and add the repo.
Step#1 Install Sam Bingner’s SAM (Subscriber Artificial Module) package. I recommend that you get it from repo.bingner.com since older versions have a different interface and may not work for this purpose.
Step#2 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#3 Go to utilities and select “De-Activate iPhone”, your ActivationState under “More Information” should now be “Unactivated”
Step#4 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.
Step#5 Go to More Information”, copy or write down the IMSI in “SAM Details”, then tap “Spoof Real SIM to SAM”.
Step#6 Go back to the main SAM screen and change your “Method” to manual. Paste or enter the IMSI string we saved in Step 5.
Step#7 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#8 Unplug your phone, close iTunes.
Step#9 Disable SAM. The source article says to uninstall SAM and delete your lockdownd folders; it’s unnecessary.
Step#10 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#11 You should see signal bars in a short time, congratulations.
Step#12 Push notifications may stop working after this procedure but can be easily restored with “clear push” utility in SAM followed by connecting to iTunes.
“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.”
Since it does not involve emergency numbers or IMSI spoofing it will not have any of the issues associated with SIM interposers. Tested working on iOS 5.01 but should work with tethered 5.1 too.[Detailed Explanation With Pics]