Factory IMEI unlock is the safest unlocking method for all iPhone models among all other solutions. Not only it is fast and affordable but it is also the only way to unlock any iPhone model, any baseband and any version of iOS, including iOS 6.1.4 / 6.1.3 and the new iOS 7.x versions. There are a lot of companies that promise to perform unlock by IMEI code but not all of them can be trusted.