As a note, this is arguing from a position of power. Some people appear to be generally incapable of textual communication; if they don't get to call you or meeting you face to face, they aren't interested in dealing with you.

edit: I'd rather use textual communication; I feel its more precise, more document-able, and you have chance to really think about what you're saying. Of course I can deal with other communication modalities, but... eh. Not as optimal IMO. :-)