When we had a landline I changed our number to a private number because of the solicitation calls we received all the time from people who wanted to sell something or from politicians who made robo calls. The calls stopped, but then I bought a new phone (Panasonic) which had a audio Caller ID, which let me know who called. If I did not recognize the number I did not answer the call.
I have a specific ringtone on my smartphone for numbers that I do not recognize and will not answer, and will put it in call-reject.