The usual "this is your second notice" credit card scam phone call. I've gotten where I throw the number in Google as fast as possible and decide to answer the call based on what I can easily find. That and I have an audio file that plays the disconnect tone and message from the phone company.
The caller never leaves a voicemail or message. When I called the number, an automated prompt gave me the option to remove my number from their call list.
I do the same thing it stops them. I did have one call me back after i blew the whistle in his ear and start complaining how it was rude so I cut loose again with it and told him he should not be dumb enough to call back.