There's a prank call podcast called The Snow Plow Show, and the guy set up a bot at a phone number that will automatically reply to callers with voice clips from a lady who yelled at him in a prank call one time. So fans of the show will put the number on windshields or craigslist ads so people will call the number and get yelled at, and the calls are all recorded so he can listen back to them later and pull out the better ones.

I think you should utilize a similar technology for your phone numbers.