There use to be free unlocking calculators for the old phone models. But it seems that it's impossible to unlock a modern phone for free. What I don't understand is how it works nowadays. You have to send the IMEI to a reseller, then wait for days (1 to 5) to get your code back.
I thought that smart hackers were profiting from their own unlocking calculators, created by themselves, but it seems that the delay getting the code is because some databases have to be accessed. And depending of the company that locked the phone that could be harder and more expensive to do.
So, how does it really work? Who are the original sellers and unlocking code creators?