The BB "Tour" was a world phone. CDMA and GSM. However, the CDMA part was locked down to your local carrier (say for example Verizon) while the GSM/Sim card allowed you to go international and just buy "local" sim cards. From my understanding though, it would still be "locked" to the CDMA provider that sold it, as is the case with pretty much every CDMA device I've heard of. And from my experience with CDMA phones, you cannot take a CDMA phone from one provider to another. It is dang near impossible to get it done and still have full function. (for example I checked to see if could take a CDMA blackberry from my provider and transfer it to another provider. Result? 3hrs on hold, 2 techs, and end result? Both providers would have to agree to it (not gonna happen) and even if I did get both to agree, once the BB was released from its origonal carrier and hooked up with a different CDMA carrier -- I'd have voice and texting abilities but no data. And no way to change that unless I stayed with the origonal carrier.
Now, I realize BB is not Android, but I think in this case it's more about the carrier then about the device. Hope this helped...