Next up, develop a flexible script that they use for study and facts only--not to read from on the actual calls. This reference tool will help your team develop confidence in the subject matter.
Next up--actual dry runs--lots of them. Each team member should have adequate practice time (out loud) so he or she can develop a knowledgeable, highly professional, confident and friendly approach.
Evaluate their performances and tweak accordingly. Be honest with yourself about their abilities, as an initial bad impression is hard to overcome. If they are not up to the task, consider working with a professional organization like ItsYourCall.com, to achieve your long term objectives (happy clients and repeat business).
Good luck with your training!