Yeah, good phone. Structurally unsound, buy a good case, etc. 10-bit color display, nice speakers, dummy good battery life, install Nova Launcher Prime, you already know what this phone is if you're thinking of buying it. Thumbs up emoji.
ANYWAY. Was worried calls or 5G wouldn't work on AT&T. They do, for anyone checking reviews about that. BUT. I've been carrying around the same SIM card for like 8 years, and as far as AT&T is concerned the last phone I had on their records was like the original iPhone SE that looked like an IPhone 5 way back in the day. Like 6 years ago. Idk.
My plan if they caught on, or if I ever need a new SIM card, is to call and say I bought an iPhone 11 or whichever the last one that had a physical SIM was, use a made up IEMI number, get that registered, etc.
But hey, no such trouble. Old AT&T SIM works fine. VoIP, calls, 5G, the works babyyyy. Thumbs up. You'll be fine on AT&T as long as you throw an old SIM that you know works in there.