I worked for a fundraising event once. The callers called in to us first and then we would transfer them over to the celebrity call line. Pretty sure it was random who they'd get and the interaction probably lasted all of 30 seconds. Just some basic sympathizing back and forth. We listened to the call until they were ready to donate and then we took the call back over to process payment. We weren't any where near the celebrities (like a completely different state), but I did get to speak with Ray Romano briefly during one of the calls.