My experience visiting two years ago, it was spotty. If you're in town or along an interstate, it's usually good coverage, but maybe not great speeds. E.g. my

My experience visiting two years ago, it was spotty. If you're in town or along an interstate, it's usually good coverage, but maybe not great speeds. E.g. my phone would show 5 bars coverages, but the speeds were noticibly far slower than what I get in Chicago. I was able to get serviceable, if albeit slow 4G LTE coverage at my parents' home about 7 miles out of town and about 1000 feet on the side of a mountain, but sitting in town at a brewery with a cell tower in sight out of the window, I couldn't get any signal at all. I presume the tower I could see was from an incompatible network. In Montana, I've been able to get surprisingly strong signals in places I'd least expect it. E.g. I was hiking in the Bitterroot National Forest up Lolo peak, and I had near perfect coverage for nearly my entire hike as far back as 2006. But, if you head out into north eastern Montana, you may well find yourself in a dead zone for quite a while. I dont know if it is still the case, but used to be cells were useless anywhere near an ICBM silo (of which there are quite a few along route 200 east of Great Falls, MT - I attended a boy scout camp a few times out that way in the late 90s). Regarding 5G, not sure it would help much in my parent's situation as I understand it is even more reliant upon line of site and more susceptible to interference from weather. There are decently sized mountains blocking them between the closest decently sized city and them. There would probably need to be a series of relay towers to overcome that.