"I feel like I playin' cards with my brother's kids again."
If you happen to be walking with someone with a cell phone who continually answers it/uses it, and it bothers you, stop walking with him. If they are headed in the opposite direction on the trail, just how are they bothering you by talking on their phone? This is a shelter issue, and away from shelters it isn't an issue unless you are a self-centered, deluded-Walter Mitty/Daniel Boone wannabe.