Look.........going to the golf course is a commitment of time, just like going to The Opera, The Ballet, or a Broadway musical....you don't talk, call, or answer your phone at these places (at least I'd hope not) so why should the golf course be any different for your 3 - 4 hour round.
If there is an emergency, anyone could leave a message on their respective voicemail suggesting to contact the Pro Shop, or even as a last resort "forward their cell number to the pro shop" (maybe for the Doctor Types or people expecting news on a preganant wife or other such important activity)
If you can't break away from your phone for 3 -4 hours, then perhaps you should take up a new sport like Racketball or Backgammon.
I once saw "Jim Gray" formerly of NBC now I believe ABC/ESPN get on his cell phone before he tee'd off, and proceed to talk on it the "ENTIRE ROUND" at a club in Atlanta.....he put in on the seat of the cart between shots, only to pick it up and continue talking for nearly 4 straight hours!!!!!
What a JOKE!!!!!!!!
I also played in a USGA Qualifier recently, at a top 50 club in the mid-west, where I had never once seen theis club hold a qualifier. During the practice round, I saw a guy bantering about on his phone, totally oblivious to anyone or anything going on around him. I went up to the guy, and promptly told him, "It's assholes like you that make Prominent Clubs scratch their heads and think twice before holding events such as this, now get off the damn phone and be respectful..JERK"
The guy shot 94 in the qualifier.....go figure, he didn't belong there in the first place!!!!