Sounds like a hotspot plan. Looks like rates are decent. We use Consumer Cellular and they offer service through AT&T OR T-Mobile towers depending on which are have better coverage for your area. We use the AT&T towers as we switched over from AT&T and have the same signal/4G LTE coverage. Unfortunately, while CC allows your phone to be used as a hotspot, we only have 15 gigs of data. We use our phone as a hotspot while camping for internet use if wi-fi (at campground where we are staying) is poor. 400 gigs of data is probably enough if you stream Netflix or the like; not sure about other uses like gaming. Also can't comment on the modem they supply but it is essentially a hotspot (so you don't have to use a phone) and not sure if there is an external antenna port on it which I would think would be a great idea if they wanted to sell product to RVers.
Also, when you compare "unlimited" I know from personal experience that can often mean unlimited data on your phone but not for use with a hotspot. We left AT&T as they conned my wife into switching to a too good to be true "unlimited" plan and the same day my hotspot (previously used for business internet) data access was shut off. The sad thing is they wouldn't let us revert to the previous plan where a hotspot could be used and we were pay $130 a month for phone and 32 gigs of data.
https://www.rvmobileinternet.com/gui...le-and-sprint/