I would have your classes over the phone...or even with cell phones in different rooms if you are in an office. Telephoene classes need to be very planned out so that the student knows where you are going, but I think they are very good at helping students BELIEVE that can speak on the phone...when their confidence seems to be the main issue.
Do some role play situations over the phone. Get him to tell you the typical situations that happen over the phone and call him and pretend to be a collegue or someone. You have to get pretty creative but it is really fun. I have done this a lot with students who work over the phone and they respond very well.
I think the best thing is making problems for them. If you know they have difficulty giving directions ask for directions. :) It makes them work hard and sweat a little but it is safe with you on the other end of the phone. :)
Hope that helps
LEARN ENGLISH BY USING IT: ANSWERS & MOTIVATION FOR ANY ENGLISH LEARNER