For a landline, you sign up online at https://www.nomorobo.com/ and it's free (you need a VOIP line for it to work, I think). I find it works great at stopping most calls on my landline. If the phone rings once but not a second time, it's a robocall that was stopped and I love when that happens. For the cell, it may cost a nominal amount but it does identify the robocalls. Give it a try.