My neighbor is a retired farmer and had a half dozen mobile units in his garage so one day I got one and an antenna (I help him to use all the stuff he has accumulated over the years) and put it in the truck. Seldom hear anything around here, maybe once and a while on the road. It was free so not a big deal but really would not be worth the cost if I had to buy one.
Best thing to do is get a list of emergency phone numbers when you are traveling and keep in the cab with you and use the cell phone, or like I do if I need a number when on the road is I call one of my kids at home and have them Google the number (free long distance is great).