The GSMA IMEI database is a global database ...
The GSMA does maintain a database of IMEIs. Its primary purpose it to ensure that no manufacturer ever accidentally ships a handset with a duplicate IMEI that has already been assigned to any other handset from any other manufacturer anywhere else in the world at any point in the past.
The GSMA also maintains, as part of that database, a blacklist. However, participation in the blacklist is totally voluntary, any carrier is totally permitted to ignore the blacklist status of any IMEI appearing in the database. The phones themselves have absolutely no knowledge whatsoever of whether or not their IMEI appears in the blacklist.
So, even if a particular handset's IMEI is blacklisted in the GSMA's database, the phone will still work perfectly fine when used in conjunction with any carrier who chooses not to participate in the voluntary blacklist. For example, none of the major American GSM operators participate in the GSMA's blacklist program.
I have never seen any evidence whatsoever suggesting that the GSMA's IMEI database plays any role whatsoever in determining a phone's SIM lock status. Indeed, most phones (other than the iPhone) have total internal control of their own unlock status, requiring a simple password to be entered to remove any locks that may have been imposed by the phone's own firmware.
So, no database, be it maintained by the GSMA or by anybody else, has anything at all to do with enforcing the unlock status of the vast majority of GSM phones on the market. I see no reason to believe that the GSMA would go out of its way to enforce the SIM locking configuration of one particular make of phone (the iPhone) when they don't do it for any other make of phone on the market.
The iPhone's unlock database is linked to a connection with Apple's servers through iTunes. The simplest explanation which fits the publicly available facts, which thanks to Occam is most likely to be the best explanation, is that Apple maintains the database, and therefore Apple is ultimately in control of the process. However, Apple has contractually obliged itself to obey the wishes of the carrier through whom the phone was sold, and therefore if Sprint sold the phone, then it would be up to Sprint to give Apple permission to remove the lock. In the absence of any such permission, Apple will refuse any request to unlock the phone.
If you have evidence to the contrary, by all means I'd love to be proven wrong.
