Same thing that most people experience. They call when i am at work so I don't answer. They never leave a message so I don't call back. Nice to know who it is so I can just block it and forget.
When are you people going to get SMART! The the damn number back I do right away if it does not work then it is a SCAM plain and simple this Phone Number .....................IS NOT A WORKING PHONE NUMBER THEREFOR IT IS A SCAM!
You have done exactly what the scammers want you to do. Call the number back. Many of these 'Not a working number' messages are fake. The scammers have computer generated recordings. This will result in more calls as your number is listed & sold. Here's an even smarter idea - don't call back numbers that you do not know. Don't believe me? Why don't you take a look at all the downloadable phone message recordings:
http://www.thisisarecording.com/
This is just one site, there are others.