AT&T is my service provider for my phone. I have a iphone 4s and am eligible for my upgrade?

AT&T is my service provider for my phone. I have a iphone 4s and am eligible for my upgrade?

Added (1). I would like to purchase the 64gb iphone 6. Can anyone tell me of any other charges I will have to pay prior to getting the phone or will I just have to pay the $299. How much will it be after taxes? Will I have to pay an activation fee? I heard something about a 40 dollar renewal fee for the 2 year contract?

You're eligible for an upgrade every two years. Since I don't know when you got your phone I can't say.