IPhone 5 sim card activation?

I got an iphone 5 for christmas. I previously had an iphone 3. The new iphone came with a new sim card & i have the sim card in my current phone (iphone 3) Is there anyway to activate the new iphone 5 so i can use it? All att stores are closed today. Just wondering if i can get it working today. No big deal if i can't! Merry Christmas!

Call the phone company you are with and call and ask if they can transfer your data to old phone.