Since I got a new phone and new plan with AT&T, I have an old Nokia 5165 phone that is just collecting dust. I want to be able to buy those pre-paid cell phone cards at wal-mart and other places. I will be giving this to my dad since he doesn't have a cell phone, just in case of emergencies and if someone needs to find him. Can I just buy the cards or do I have to go through some special process?