The Chinese iPhone hacker Loktar_Sun has, according to a number of reports, released an unlock method that supports Apple’s iPhone 4S. In order to take advantage of the solution, all you need is a jailbroken iPhone handset that iTunes is recognizing (i.e., that hasn’t been blacklisted).
Already, a number of unlock solutions such as GEVEY SIM and CutYourSIM promise to unlock the iPhone 4S, for $55 and $185 respectively. The new method, which utilizes Sam Bingner’s SAM (Subscriber Artificial Module) package, comes with no such price-tag. However it does have its limitations, as iDownloadBlog notes:
[T]his unlock method will only allow you to use the SIM card that you use to unlock your phone with, so you will not be able to freely switch between SIMs. It’s an unlock, but it apparently still has limitations when compared to a true factory unlocked phone.
Therefore, the best way to get your iPhone unlocked is – if you’re eligible – to contact AT&T, and have them unlock your off-contract iPhone. However, if this isn’t an option, Loktar_Sun’s method might work for you.
It’s important to precisely follow every step of this solution, and for that reason we’re going to direct you over to his original instructions, rather then reproduce them here. According to @MuscleNerd, this method works and is legit; iDownloadBlog, too, has no complaints (save for the one noted above) to cite regarding the solution.
Once again, here are the instructions. Good luck – and remember, if you’re eligible for an AT&T-unlock, contact the network rather than use this method!