I work in a dental office and it's not that we mind patients ringtones, so much, because as we are working on them and their phone rings we can "ignore it" and they are usually "embarrassed" that they didn't turn it off...BUT...we had to draw the line when we had a rash of people trying to answer their phones while getting work done...And it's usually just to say "I'm at the dentist. Let me call you back"...HELLO! That's what voice mail is for!
The last straw was when a patient couldn't answer his phone because he had an impression in his mouth and asked the DR to answer it for him!! From that moment on, signs went up all over reading "Please turn off your cell phones".