U.S. Cellular, the top provider here in Eastern NC. They have by far the most customers and towers virtually covering every square inch of this part of the state. The analogue out there in the swamp can go from perfect to near nothing just depending on how many trees are around you.. there's only been once place though where I was that I couldn't complete a call. It's top-notch everywhere else.. it sounds like a landline for me and whoever I'm talking with.

As for the wiring question you had in the other topic (I was going to mount one of these over a year ago and I started that topic... I was suprised to see it come back like that) I wired it into the switched 12v outlet on the dash. Black into the negative lead, and both positives (green and red) into the positive lead. There are two positives coming out of the phone, one is for always-on and one is for switched, but this is only needed if you want to be able to use the phone without car keys. I didn't, so I just connected them both to the switched outlet.
I also had a yellow one that you connect to the horn and lights if you want to be notified outside of the car when the phone is ringing... that only works if you have it wired to work when the vehicle is off, and I had no use for it anyway, so I left it disconnected.