I've been to tournament rounds and practice rounds as well.... I've seen folks on a phone (over in a corner away from obvious traffic) including a friend of mine..... but I've never seen one during a tournament round. I've seen Greg Norman practically assaulted for a photo after a practice round... things are just different for tournament rounds- even the patrons are different.
I would start my walk on #1 through 9 ... then skip over to the par 3 course then walk 10 through 18 . The players are all in a relaxed mood and willing to talk sometimes but when the tournament starts EVERYTHING changes.... nothing better or more reasonably priced than the sandwiches and beer at the Masters.... go by the pro shop because you will definitely want a piece of memorabilia .... enjoy Dawg