As a programmer, I've found that interruptions are the most problematic thing that keeps me from being more productive, and nothing is more irritating than being interrupted by a pointless phone call. So, over a decade ago, I stopped having a landline, and only gave my cell number to a small number. Then I stopped carrying a cell completely.
I'm kinda amazed, in this day and age, how many organizations primary method of communication is the phone. I've had people, on multiple occasions, say "I can't do that for you via this forum, please call us at XXX".
The only reason I want an iPhone 4Steve (unlocked, of course) is because I want to have data access everywhere. The ability to make the occasional phone call for those people (usually government offices it seems) still stuck in the 19th century is a minor bonus.
If you require a phone number in order to do business with you, I simply will not do business with you.