I write out my name, address, phone number, date of birth, name of their company, what they do, interviewers name (take notes as he talks that will help focus you) all the stuff that should come "naturally" as I tend to forget them. I had to be on a panel once and tell my story and I got 2 sentences in and forgot it Fortunately I had worked so hard in therapy giving myself space and just allowing myself to relax and recover, etc. so I was able to pick up and start over rather than wholly freeze. They had given me a phone interview to see if I would be good for the panel (it was a volunteer thing, you volunteered then they interviewed you to see if you'd be okay and then you had to do the panel!) and just reminding myself I had done that helped some and the whole funny/ridiculousness of forgetting my own story? If you can laugh at yourself and find your nerves normal/funny that might help relax you. That you picked up on the fact the guy calling might be feeling nervous too, pretend they are secretly nervous when they call and try to put THEM at their ease?