These are Robo Calls to see if someone answers to sell the number to another company. If you don't know the number don't answer and it wont leave a message. If it is someone that wants to talk they will leave a message. Rocket Science! ;-)
If you answer that number and hang up you'll get another phone call from +1-314-214-6589 saying the same thing I hung up I called it back it was an Indian dude and I told him take me off the list he said I'll call you back and hung up on me