We have a Wilson Engineering unit called a WeBoost. It works, what more to say. Last year we were in upstate New York in the Adirondacks and had about 1-2 bars of service at the park if we were lucky. Thought about it quite a bit as they are a bit pricey but the reviews are good.
If you need Internet and phone service, it's worth the money. We went from 1 and occasionally 2 bars of signal to a solid 2 and usually 3 and also had at least 3G and most times LTE.
Now for the somewhat down side - essentially you are creating a mini cell tower inside the coach. It has a signal boosting radius of about 10' so you want to think about where to put it. In our RL, we took out the rear couch and had a desk and surround custom built for storage and a work station. I've mounted the outside antenna on the top of the roof ladder (it's still about 3" lower than the AC unit) ran the cable down the ladder with wire ties and then along the left side and in through the slide weatherstripping. The small inside antenna sits on the desk. With this setup, we've got good cell signal to our phones anywhere in the living area of the coach. Got a little iffy in the bedroom.
We also have a MIFI and of course it's signal gets boosted also from the WeBoost so we do have Internet all through the coach. We have the Verizon unlimited plan.
We also have an Alfa Camppro wifi booster. It also works. Where we are now, the wifi is only in the office that is about 600-700' away. Without the Alfa on, none of our devices or computers will pick it up. With the Alfa on, we've got wifi with a good signal.
If you buy either or both, I highly recommend
www.technorv.com. Eric and Tammi are fulltimers and run a great business. They are not the cheapest, but anything he sells, he has used and more importantly supports. Case in point, the instructions that come with the Alfa are truly terrible and you'll go nuts setting it up. If you buy it from Techno, eric sends an email with both written step by step and also a video on how to set it up. Buying it from him will cost you an extra $20. Trust me, it's more than worth it.
Hope this helps.