Phil Zimmermann, hero developer who made secure public-key encryption available to the masses with the program Pretty Good Privacy (PGP) -- and endured much tribulation because of it -- has figured out a way to make his phone number available without too much difficulty to those who need it without making it too obvious for those who don't:

To reach me by phone, please read the following:

(1) Some people tell me that it is not a good idea to put my home phone number on my web page. (6) They say that I will be swamped with phone calls from everyone who has a question about how to use PGP. (5) Experience has shown that they are right. (0) I would rather that people who have questions about how to use PGP read the fine manual, or failing that, contact PGP Corporation to ask those questions, or, failing that, ask any other randomly chosen private citizen who knows how to use PGP. (3) But I want to make it possible for some people to reach me directly; journalists, for example, or prospective clients for my consulting business, or sales inquiries from corporate customers who want to buy more than a few copies of PGP, or any other business contacts.

Interesting way to number his points, isn't it? If you really need his phone number, you really will have to read the whole thing.