If you are cold calling to sell services, you shouldn't be reluctant to provide verifiable business and caller information. The only conclusion we can draw from people who don't is that you are dishonest scumbags.
when ever I block them, I just get another call from someone else. I said to myself, I must be on the sucker list.
thinking the calls are coming from, I let a friend use my number for a job. and ways we go.
If that "friend" put that number on job search web sites, then that is how you got on those lists. Scammers harvest numbers anywhere they can, job search, Craigslist, Facebook, etc.