I use AT&T on an HTC One as a Hotspot for 2 laptops, and a kindle. My DW has an HTC Inspire 4g, which is our backup if needed for another hotspot. I used the HTC Inspire until a couple of months ago when I went to the HTC One.
For 3 months I used an ATT partner when volunteering at Big Bend. I talked with ATT, they covered my service with the partner site for the 3 months. I was only suppose to use 25% of my plan on the partner site. ATT never cut me off. I never went over my 5g plan.
I have not yet been at a location East, Southwest where I have not had ATT access.
Works for me. Volconus outlines the locations we have been for extended periods using ATT.