On the LA board, Mike Kilgore has this to say:
"My wife had one of the employees of a new, and very popular restaurant in her store today who said that, because prospective diners call and can't get a reservation that night at their desired time, they are so abusive on the phone with the GM that he is having a very hard time dealing with it emotionally. I would like to have some opinions on how prevalent this type of behavior is, and if anyone would like to fess up here if they have been guilty of something similar themselves, I would be interested in their reasons? I can't understand that type of thinking, and would simply say "When can I get a reservation for the time I want." But evidently this is much more common than I could have believed before today."
I'm a very wimpy, non-combative person, and I can't imagine being abusive to someone in any situation. I do have one suggestion, though. One of the things a restaurant employee can do that might diffuse this kind of situation before it gets started is automatically suggest an alternative-- either a time that same day, if possible, or another day when the particular time the caller wants is available.
Your wife should also encourage/remind this person not take the abuse so personally; the caller is mad at the restaurant and/or his or her own failure to call earlier, NOT at the employee. If all else fails, maybe this person could do something other than answer the phone, and a thicker-skinned person can take over.