I honestly do not know if Call Of Duty is like that but I am guessing it is. The "regionalizing" is only for online play- the games will play on any PS3 in the world but I think you are only able to connect to servers based on where your PS3 is intended for (in your case Hong Kong). To my knowledge there is no workaround for this. Which region is your copy of the game originally intended?
This is just the type of thing happening that Sony wanted to avoid by blocking imports of systems before the official launch.