When I hire a large group of callers, I conduct group interviews. Each group interview lasts about an hour and 15 minutes and I have found that about 8 potential callers per interview is a perfect number.

I have them separate into groups and find two things they have in common and I take notes on who writes things down, who speaks, and who isn't shy about sharing ideas.

We also do some role-playing where I give them a script and each of them takes turns making a 'pretend' call. This is really helpful because it is quite awkward and silly but it takes someone who doesn't mind the awkwardness and silliness to be a good caller.

Group interviews really help some of the interviewers shine. I did these interviews this year for the first time and it is amazing how much better my hiring was!!! I would highly recommend it. Attached is my itinerary from this year.