Next time don't answer since you don't know who it is. These are scammers. They don't care if you aren't interested. You are now on the "live list" that they will continue to use and sell to other scammers. You are now known to them as gullible enough to pick up and talk to them as if they respect what you want - also known as a sucker. Never answer for unknown numbers.
This is the recorded part of the call. They do this to make it believable since they can't predict your exact response. Once you respond to the recording a person will pick the line up. You are a fish and you have now verified that you are on their line. Stop picking up calls from unknown numbers. Any actions besides ignoring the call is simply playing into their game and giving them info that they want.