Apple says my phone is with AT&T but AT&T customer service said it's not. Why?

Purchased an iphone from Amazon. It says carrier not available and won't read my sim. I called AT&T and they told me it's not with AT&T and she also said that's why it's not working and to have the phone unlocked. I called apple and was told it's with AT&T

Juaesxyn

Get Amazon and Apple representatives talking to each other in your interest.

Get Amazon and Apple representatives talking to each other in your interest.