Well I guess so. It used to be that european phones could not be used in america, and vice versa. I don't remember why! Something to do with some technical stuff, I believe.
But maybe that is no longer the case!?
I asked a friend who knows about this stuff, and apparently, the US and Japan still have a different system than the rest of the world. So I will most likely not be able to buy the Casio Commando. Damn it! I like that phone!