How exactly could you evaluate FizzBuzz over the phone? Its designed as a weed out question early on, if they can't do that (and yes some have failed) then it makes a decision pretty easy
Most places I've interviewed at (or was the interviewer) talked to the candidate over the phone but had something like Google Docs open so you could watch some live coding. Usually just go through some very basic exercises to make sure the person at least knows how to code and ask a few, general programming questions. Stuff like that.