If a club has a rule requiring you to turn off phones or leave them in the car or whatever, I've got no problem with that. If I'm playing as someone's guest I follow that rule just as I'd follow any others they have whether I'm a guest at a club or in their home. I don't allow anyone to smoke in or around my house, and smokers don't have trouble following that rule as my guest. Its just simple manners to do as one's host asks.
However, without any rules to the contrary, I will carry my phone with me in my back pocket on vibrate so it makes no noise. Usually I don't feel it vibrate (especially when its breezy) so if I may receive an important call I'll discreetly check it every few holes, and if I decide I need to listen to a message I'll do so when walking to my ball or waiting to play when I'm away from others. The time taken to check a message is less of a disruption to the group than someone excusing themselves to the restroom. I won't make or return a call unless I'm playing with people who are OK with it, and will do it out of earshot (for multiple reasons) If the people I'm playing with have no problem with it, and it has no possible impact on anyone else on the course, I don't see the problem.
I realize the bans are necessary because some people are too inconsiderate or too forgetful to turn off or silence their phone when they arrive at the course, etc. Believe me, I see the bad side of this during scrambles where people who only play a few times a year are just socializing and might take a dozen calls during the round and it can be pretty annoying.
I work as a consultant in high tech, mostly with large firms as clients, and for better or worse it just reflects badly on you in this field to be out of contact for half a day on weekdays. They're fine with it if I'm able to return their call and tell them I'll get back to them later via phone or email. I usually tell them I'm running errands since people stuck behind a desk don't always want to hear about other people doing what they wish they were doing