over in the "OnePlus Says It's Talking to US Carriers About a 5G Phone" discussion:
"Support for AT&T" is......
Not true support. One can use the OnePlus 6 on AT&T and it will work perfectly, with the exception being no VOLTE / HD Calling / Wifi Calling. That said, these are NOT OnePlus's fault at all... they are entirely AT&T's doing.... AT&T will not allow any phones other than their own (or the Google Pixel) to access it's VOLTE & HD features. Works on T-Mobile with zero problem.
Seriously? I know it's sort of a budget high end device per say but damn after 6 iterations you cant up the ante a bit and slap a 2k screen on it? Especially since it's a big ass 6.2" incher? Come on smh