I'm from Taiwan. Recently I bought an unlocked 8830 World Edition (Sprint) from e-bay USA. My mobile service company is through CDMA 2000 frenquency. When I insert my SIM, It can search the signal and the contacts of SIM. But I can't make any phone call, due to Taiwan have no RIM service center, I don't know how to do!! Anyone who can help me???? please!!!!!!!