I look at talking on the phone in the bathroom the same way as taking selfies in the bathroom...some things you don't do just because it's crass. If I'm desperate enough that I have to use a public john, I don't want to listen to some jackwagon chatting away while dropping a bomb next door. If I could fart on command, on a scale of fizz to tearass I'd not stop at anything short of a ripgut.