I've been on the DNC list for a long time and it is hard to tell the difference in call frequency from before to after. In other words, it only keeps the honest telemarketers out.
I don't have caller I.D., I'm not gonna pay for that.
How do you get their number or identity? Caller I.D. numbers are often spoofed, and when you ask them they hang up. I find it hilarious that they expect people to do business with an outfit that refuses to identify themselves. However, they are able to succeed because evidently there are millions and millions of idiots that actually do give them "business", otherwise they wouldn't be there.