I hate the interruption of whatever it was I was doing more than anything. Once I'm talking it doesn't much bother me unless I get bored. Tone of voice is adequate for me in place of body language, probably because I mostly only talk to people I know pretty well, plus I'm kind of an auditory/verbal brained person.
Agree with all this, especially the unwanted interruption part. Also, phone calls often involve questions that completely leave me off guard. That's why I prefer to be the one doing the calling rather than receiving it. It's easier to go over what I want to say that way.
5w6 or 9w1 sp/so/sx, I think