Took them a long time!
5 years ago I bought a code online to unlock my BlackBerry. The vendor did not explain how he was getting the code, but I'm pretty sure that it involved a telco employee with access to the system used to provide unlocking numbers.
Now the real question is "how come it took them so long to notice?" A simple comparaison between the number of codes requested through the official channels and the number of codes issued would do the trick.