Ten percent of the world has cell phone coverage. Obviously, that also means that 90% of the world is outside cell phone range. That includes a lot of places where RVs (recreational vehicles) travel.
Most interstate highways have excellent cell phone coverage, as do most metropolitan areas. While RVs do spend a lot of time on the highways, they also appear in rural areas more often than in cities. I have stayed at more than one RV resort where the cell phone coverage was either spotty or non-existent.
How about data coverage? Can an RV owner surf the web or send and receive e-mail? The answer is... "sometimes." Some campgrounds provide wi-fi coverage while others do not. Many RV owners purchase "air cards" to connect laptop computers to the Internet via a local cell tower; but, air cards have the same limitations as cell phones: they don't work too well in rural areas beyond the reach of the nearest cell tower. Air cards are useless in 90% of the world.