As a B2C business, I get idiot phone calls all the time from people expecting hand-holding while they place their order online.
I've spent hours (days) formulating my web site, writing a well-thought out FAQ, and answers to all major questions. Yet, still I get lazy customers (who usually spend the absolute minimum) calling me and wasting untold hours of my time to satisfy their inability to read.
While having a phone number on your site may raise trust, it's a invitation for the idiot to call.