BlackBerry 8830

That would depend on your carrier. I am with Verizon, and they have told me that they would not unlock the phone. However, it utlimately remains to be seen, because in some foreign countries, it is illegal to lock the phone from being used with different SIMs. Given CDMA carriers' lack of experience with GSM, I suspect that in time they might offer to unlock the phone, as do some GSM carriers. Good luck.