Do you have a landline phone which displays the incoming number? Generally when these calls are made they are testing to check the validity of the number, so by answering it confirms the number is attached to a person and is a live line. Normally a dialler will try a set number of times to confirm the line and then give up if unsuccessful.
What this means is that by answering and confirming validity, your number will then be sold on again and again as it’s confirmed as “live”.
If you have or can get a landline with a number display, just ignore the calls - I know how irritating it is!
Generally these things are cyclical, so by ignoring you may be able to disguise your number as “dead”, but it will take time.
I used to work within data management, so some of this info might be a bit out of date, but these were the methods we were trained on circa 5 years ago when more of the foreign telemarketers became prevalent.