iPhone unlocks are usually a tetchy experience - you have to have the right firmware on the right model iPhone at the right time. Now, however, thanks to a method that spoofs the activation server, you can unlock almost any iPhone semi-permanently. The system, called Subscriber Artificial Module or SAM, requires a jailbroken iPhone and Cydia. To run it, you de-activate your phone, insert a new SIM, and then activate SAM. SAM spoofs the activation process, convincing the phone that it has been unlocked properly and without issues.