My friend got a new cell phone and gave me her old one. How do I use it with prepaid phone cards?

gardenduo2005 asked: When my own Cingular contract was complete, I bought prepaid phone cards for my Nokia phone. Now that my friend’s Cingular contract is complete, how can I use her old LG G4015 phone with prepaid phone cards, considering that she transfered her phone number to her new phone? Will this involve SIM cards?Add [...]