ok I just bought a iphone off ebay it's having poxel and shadow problems
it's a 8gb so I'm guessing it would still have a warrenty on it but idk but I want to get it replaced if it is so I'm thinking about going into a apple store and getting it replaced but do i have to be a at&t customer or can i put a at&t sim in it what all do i need to do to replace it? how much will it cost
The warranty is not void if you dont have ATT. That would mean that the warranty is void for anyone who walks into an apple store, buys a phone and doesnt have an att account.
Just restore it, register it on apple's support site to your apple username, then call 1800-my-iphone and set up a repair on it. Ive done it with my gf's iphone that uses tmobile.