I think it's an advantage of the phone that there are less visual cues, so you can concentrate on auditive cues. A non-geek on the phone is somewhat in the situation of a geek, because he is aware of less non-verbal signals. He will tend to compensate with more auditive signals and clearer indications in the content of what is said. Fewer signals with more significance are easier to see for the geek.

At least that's what I used to think when face o face conversations were still a big problem for me, but phone conversations felt easier.

It seems I have become much less of a geek over the years.