Like most one liners, that's not very fair. I don't even know my own phone number. Why would I? I consider it bad interface that I have to ever even hear this kind of technical detail at all. I know my number and every other number by the name of the person or place I want to call.

Likewise, are you sure the people are looking in their document because they don't know? Maybe they answered this question at some previous time in a really concise and elegant way and want to reuse it? Maybe they have a page in their that visually illustrates the answer?