I drive from one side of MT to the other on a regular basis. Verizon is what I use. Most places that I don't have signal there is none no matter what you use. The state DOT changed from ATT to Verizon several years ago and most crews that Ive asked are happy that they no longer need to use their personal verizon phones to have service. Ive been in one place between Monida and Lima that verizon didn't work so one guy on the crew was given an ATT phone.