Can you change the Sim card from AT&T?

I have an iphone 5s white 16gb, my dad has a black iphone 5s 64gb or 32gb i don't know, neither does him. He barely uses any memory, but my phone is already full, my dad said he would trade his phone with me no problem. Can i just switch the SIM card and will it work normaly? Or should i take it to apple or at&t?

If they are on the same network, then yes, it should work straight away.

If not, you need to get your Dad's iphone unlocked.

That's nice of your Dad. Don't forget the Father's Day card.

Assuming both are on AT&T then yes, its just a matter of swapping SIMs (& of course the data on both). If not, then they both would have to be unlocked 1st to be able to swap SIMs.