Sim card-iphone 5 to galaxy 3
I am using a iPhone 5 at the moment. I have a phone of a family member that is a galaxy S3 that is not being used and the line is deactivated. I am wanting to use the Galaxy instead of my iPhone for now. I know I need a Micro SIM card to use, will I need to get a new one at the att store or can I use the one it has to be able to use it on my line, and just need to call and get my number to use on the card?