Intelligence is directly proportional to the square of the distance from a telephone.
Well, at least for me, it is. A chat gives me time and room to think, unlike a telephone call.
I currently take chats from the low-level techs who actually take chats and calls from customers (which is a demotion from actually working support tickets, but I digress). I can and have done chats from customers, but I loathe the telephone, at work and in life.
Phone calls are good for dealing with stupid people, because stupid people (well, actually, most people, including some intelligent people) don't actually read words, but they do hear and react to the tones of voice, which is useful for getting through to them.