I've been on both sides of this issue, and have kicked myself when I forget to turn off the ringer. I really don't want my time on the course interrupted. I always carry my I-phone though, mostly to check local radar and to check for calls at the turn. But also for emergencies and to call the pro shop about the a**holes that just drove across the green in their cart!(really happened) When other players make or get calls, it use to bother me, now I try to let all those kinds of distractions roll off my back. I've never scored well when I'm pissed. So, carry them, but turn off the ringer. Focus instead on your game, your friends and the fact that you have the time to enjoy both and the world around you. Oh, I can't see myself ever using my phone for keeping score, too distracting plus I want a hardcopy of my score.