partial_accumen

In the case of the OnePlus 6T, only the T-Mobile version is ‘supported,’ when the unlocked version is the same in all other markets (including the US).

I’m seeing two models of the OnePlus 6T:

• 6T (A6013) This one is on the list of AT&T approved devices and most importantly has LTE bands 30 and 71 which are used in North America. source
• 6T (A6010) This one is made for the Chinese market and has the following LTE Bands: 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 29, 32, 38, 39, 40, 41, 66. Notice that North American LTE bans 30 and 71 are missing. source

Are you aware of a different 6T model besides these two or are you saying there are 6T (A6013) that AT&T are rejecting from activating on their network?

My phone at the time worked fine on 4G for over a year, but suddenly one day it no longer worked once they started enforcing this. I suspect the carrier wanted to collect a troll toll from phone manufacturers to allow them the privilege to sell a phone to their customers

Its certainly possible that they’re trying to extract a toll from handset manufacturers, but I could also see it being a spectrum consolidation. Can I ask if your OnePlus 5T was a model specifically made for the USA market or was it imported from China or Indian markets? I’ve seen non-domestic model phones not contain all the same radios as North American phones. So while its possible there were a few specific bands overlapping that allowed it to work, those bands could have been deprovisioned from phone service or sold off to other companies wanting to buy spectrum.