Can a Bell Blackberry work with a network that doesn't use sim cards?

Hey my friend is giving me a bell blackberry and I'm gonna unlock it. The thing is that I'm moving to Argentina where the phone companies use sim cards.
so I guess my question is, would i be able to put a sim card on a bell phone and if I unlock it would it work in Argentina?
Thanks so much, you guys are great =)

What is the mobile model? If its CDMA it can be unlocked and hence it cannot be used with other sim cards. If its GSM, it can be unlocked either through network provider or third party unlockers like Mobileunlocksolutions.com and then the networks can be swapped with your Blackberry.