Most carriers (cellular and home) have a blocked number list you can add your numbers to. On smartphones, you can additionally download many free spam screening apps such as truecaller that will alert you and allow you to block them as well. And you can also add your home number to a free service called nomorobo that when it detects robocallers, lets it ring once and hangs up on them. Might work for cell too, but havent tried it. These should certainly take care of your persistent caller, and a bulk of the others you might get.

Many phones (smartphones and things like cordless Panasonics for landlines) also have onboard number blocking independent of the carrier. No app needed.

I regularly get one or two calls per day. There are three different messages (same voices, etc.) but always from a different number and area code. They never leave a voicemail message. One is for my non-existent student loan, one is for home security, and one is for solar panels.

You can try complaining to your Atty. General's Office. In my state we have a state no-call list and the state will take action if there are enough complaints.

I agree with toxcrusadr, did the same and it worked for me, no more calls