SCAMS.
In agreement with the previous posts but I have changed my position on "wasting their time". Did that for quite awhile as time, mood, and circumstances permitted.
Does not stop them and only flags your number as being "live". They sell your number over and over and you will get more and more calls.
I had gone to the extent of looking up and printing out the website screens of the sites they wanted me to go and download stuff. Usually some software that would give them access to and control of my system.
When they called I unplugged my network connection but could pretend I was connected (by describing where I was "on the screen") as they told me to do. Claimed Error 404. Typed letters "D" 'O", "T", instead of a period...