That's the simplest solution.
We have our land line phone on Spectrum, which has a free robo call blocker. Very effective, one gets one ring to announce its operation, and done. On my cell, I have built a substantial blocked call database, so they don't get through. When they use a new number, I'll answer, caller ID showing it's someone I don't know, and use a variety of accents, mostly to show the sucker on the other end it's going to be difficult. "Who dis?" I'll say. Generally they'll answer with some bogus charity or a cruise. "Wha' you want?" Or, I'll do the next line in another language. I have had them hang up on me. YES!

Then I add the number to my block list. I dread ever having to change my number, because I'll lose my database.
Hurrah for the Bonnie Blue Flag that bears a Single Star.