I think FizzBuzz is a fine question to ask in an in-person interview with a whiteboard or pen and paper handy to determine whether or not a particular candidate is of bare-minimum competence. However, it does not work as well on phone interviews because any typing you hear could just as easily be the candidate's Googling for the answer (not to mention the fact that reading code over the phone is less than savory).

Are there any phone-interview questions that are equivalent to FizzBuzz in the sense that an incompetent programmer will not be able to answer it correctly and a programmer of at least minimal competence will?

Given a choice, in my particular case I am curious about .NET-centric solutions, but since I was not able to find a duplicate to this question based on a cursory search, I would not mind at all if this question became the canonical source for platform-agnostic phone fizzbuzz questions.