Cuttyhunk/Maine Coast
The only place I had a problem was once on Cuttyhunk Island, MA. It was just out of range of the nearest tower. Now, last summer, I was out there and had no problems with a signal.If you head up the coast of Maine, there is intermittent service. Some of the less populated areas between Portland and Mt. Desert Isle. This would primarily be mid-coast Maine where I experienced that. Downeast is more difficult. But things are improving as the popularity increases up there.On another front, if you were to make the run from Plymouth to Provincetown, you may hit a dead zone about half way there where you won't be able to reach a tower.In January I took a fast ferry from Naples, FL to Key West. There was a short segment in the middle of the 90-mile run where we had no service.Back when I got my first cell phone, the service provider asked me what I would use it for. I told them that I would primarily use it on my boat. They suggested the bag phone, at the time, because it threw a stronger signal that a hand-held phone.