Hi British bulldog.
In my experience, it depends very much on the assessor. Some are happy for the claimant just to confirm their name and then allow the appointee take over, some want to hear from the claimant, but are happy for the appointee to take over, some want to hear from the claimant, but at the end will ask if the appointee wants to add anything and some don't all the appointee to talk at all (which is completely wrong). I think the best way is for the appointee to answer the call first and set down what the assessor expects and what you expect and know from the claimant. Do it gently and most of them are reasonable.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
