I heard on the news the other day that they often use the first 3-6 numbers of your phone number (spoofed, of course) due to when you see it, it looks like a familiar number and you are more likely to answer. I know when I get robo calls, typically for resorts or cruises, they often start with the same numbers as mine.
I would advise just hanging up and definitely not clicking to remove your number as that lets them know the number is good and they can sell it for more money. You end up allowing them to make more money and getting yourself more calls...
Unless I am expecting a call from someone that I don't know the number, I don't answer. If they are legit, they will leave a message and I will return call.
