Despite coverage maps, I've found over the past years of traveling from Texas to Florida to Maine to California to Washington that cell phone coverage is spotty at best if you get away from major interstates/ highways.
Especially if the road travels through mountains or along coasts.
Drove up US-101 from Tillamook, OR to near Aberdeen, WA yesterday. Had ATT coverage 80% of the distance til we crossed the Columbia River, and less than 25% of the time up through Washington. Verizon coverage was a little better in WA, a little less in OR. (Yes, we have both AT&T and Verizon cell phones, because we've found both have gaps in coverage, even along the east coast.)
Huge stretches of US-101 are with no cell coverage at all along the west coast.
When we drove down CA-1 from Monterey to Big Sur in April - there was almost no cell coverage at all once 10 miles south of Carmel. Wasn't even enough coverage in the town of Big Sur to use Facebook. Just SMS only.
Our general rule is to expect no cell coverage when we are 10 miles or more from a city of over 5,000 population.
We've had no cell phone service at campgrounds for 28 days this year in California - Jamul just outside San Diego, Groveland near Yosemite NP, Sanger near Fresno, near Eureka.
No cell service for 17 days in Oregon in Trail near Medford and Pacific City.
No cell service for 44 days in Washington - near Chehalis, Monroe near Seattle, La Conner, and near Ocean Shores.
Full-Time 2014 - ????
โNot all who wander are lost.โ
"You were supposed to turn back at the last street."
2012 Ram 2500 Mega Cab
2014 Flagstaff 832IKBS TT