Hi, I haven't heard about the unlocking source which you have mentioned here. But from my personal experience, I would suggest you that unlocking an iPhone 4 using remote unlocking service is the safest and easiest way to do. You can get the remote unlocking service for an iPhone 4 from Theunlockspot.com at affordable cost with easy unlocking guide. This is a permanent unlocking method and doesn't require a jailbreak too.