Phone Unlocking Online unlocking sites, where do they get the codes?

[sentrypr]

I am interested in how all these online phone unlocker sites get the unlock code allowing them to be used with any SIM card just from the IMEI number?
Im guessing they generate the unlock code based on the make, model and IMEI number using some sort of equation or database but im wondering how come this information is not freely available for everyone to do it?

 

[Blartiartfast]

The old Nokias are calculated, yes, 99% of the newer handset codes cannot be generated from the mentioned details (blackberry aside). They are usually obtained from an insider. The 2 servers that I am privy to obtain the codes at a certain time of day, and on certain days... They are processed as legitimate requests, but are actually tendered by the insider..
This is why "3" network codes are no longer available.. They did a big audit.. Heads rolled. Voda are easy to obtain.... Voda simply don't care..

The codes are processed at certain times of the week, at certain times...... The "insider" is less likely to get caught at these times.. Yes, it really is that simple.