If I were you, I would consider putting yourself on the national no call list that way if a telemarketer doesn't back off when you request it, you can legally take them to court.

You could also do what I do: make your primary phone number a cheap pay by the month prepaid. Basically, I use T-mobile's pay by the month prepaid which costs me $40 a month for unlimited talk and text and 1GB of data which is cheap compared to many other companies and has the benefit of allowing you to pay via prepaid phone cards commonly found in stores via cash which ensures your privacy. You don't have to give your real name to them unless you pay via debit/credit card and even then they don't keep logs of it. I also don't have a landline which makes it pretty much impossible for strangers or people finder companies finding my phone number or having it become public information.

To provide an additional layer of privacy I use an Android app called "Burner" which lets me pay a few dollars a month for temporary disposable phone numbers which I give to companies or people who I think are likely to misuse my information or sell me out somehow if they need a phone number for whatever reason.

Adopt a similar setup to mine and you will be immune to pretty much all kinds of bothersome people including telemarketers, crazy exes, and even debt collectors