I used to have something called a "car kit" in my work truck, cost about $700 in 2003 but I could take and make calls almost anywhere in Montana which is about the worst place I ever went to get calls.
I have a Wilson booster in my pickup. I get on average ~2 bars more signal where there is signal. Where there is no signal, there's still no signal. I've got an external hard-wired antenna to pick up the signal and a broadcast antenna inside the truck that allows anyone to use the boosted signal.
Since Montana was mentioned, a place that I really noticed that the booster was working was traveling between Miles City and Billings. Lots of up/down and dropping calls in the bottoms without the booster as I-94 runs along the Yellowstone river bluffs. With the booster, I don't drop those calls.
All with Verizon. Pard's AT&T phone mostly still sucks rocks for coverage even in my truck with the booster.
