Sure they do. Mine (Android) at least, has an option to decline the call and send one of a variety of text messages to the caller including exactly that one (I'

Sure they do. Mine (Android) at least, has an option to decline the call and send one of a variety of text messages to the caller including exactly that one (I'm busy right now, call me back in an hour) with one touch. Does iOS not support this sort of thing as well?