Are all iPhone X sold by AT&T locked?
I bought an iPhone X from a friend who claimed that he bought it full price $1200 from AT&T and unlocked. He activated the phone with his AT&T sim card. Then he sold it to me. Thinking it was an unlocked phone, I bought it. However, when I tried to use it with my t-mobile sim card, it didn't work. I don't know why, told him about that, he doesn't know why either.