During a gig, my phone is placed someplace out of sight except to me, sound off, vibrate on ... If a call comes in I can see who it is and decide if I NEED to call back immediately - some sort of EMERGENCY - or if I can call back later ...
Before passing judgement - which I shouldn't do anyway - on someone using their phone during my performance, I try to determine if that person is on an IMPORTANT call or just chit-chatting ... I also dislike people getting or making a phone call while on the golf course ... If your work needs to call you while you are on the golf course, perhaps you shouldn't be there ...