I have a friend that is thinking of changing carriers (from Sprint to something else). He is also considering moving to Ohio. So I first looked at T-Mobile's own website for coverage. If we took the maps as truthful, we'd have to believe that the whole state has coverage AND it is even better than its competitors. So then I went to OpenSignal.com and checked. T-Mobile actually has the worst coverage of all four carriers.
Just to add to the above... Both T-Mobile and Sprint boast their coverage is just as good if not better than "dumb and dumber's" (Verizon and AT&T's) coverage. Sprint boasts they are so close in percentage of Verizon, that it is a no brainer to switch. The truth of the matter is much different. It must be caused by the residual fallout of the "alternative facts" we are living with today. LOL
I think they all exaggerate their coverage. Years ago, AT&T said they had 100% Chicagoland coverage and I would end up with roaming charges every month. Just a couple of years ago when I had AT&T I could still find dead spots on interstate 294