I answer they hang up.

Calls and never leaves a message. Bill collectors are getting smarter using local numbers

Call from what seems like an automated service about going back to school. It is set up to speak as if a live person is on the other end. They start out asking questions that will get a general response and will allow enough time for you to answer. She asked, what would I like to go to school to study? I asked her how did she get my number, and the response was, we can pick schools in just a moment. So I hung up.

When i answered, a recording started saying this is lisa, a risk evaluator..... And then the connection dropped.  No idea where it was going but clearing a junk or telemarketer call.

Calls over and over back to back.  When i finally get frustrated and answer, a clearly automated woman's face says, "Hi this Jo and I'm calling about a career opportunity." and then the line went dead.  No option to even be removed from their list.  Number is now blocked.