I see, even at this point, I think I probably would have either aborted the interview right then (if that's the environment they put their candidates in, doesn'

I see, even at this point, I think I probably would have either aborted the interview right then (if that's the environment they put their candidates in, doesn't bode well for actual employees), or been upfront saying something like "okay, well I'm not really going to talk while I write the solution out." That's not really the ideal situation for interviewer or interviewee, and it's awkward for both parties, so I doubt you'll come across it again. I've been on about 25-30 interviews over the course of the last 5-6 years, and I've never once been asked to code over the phone, and I don't think I'd ever ask a candidate to solve something over the phone/skype.