Annoying number

He called me 8 times and then blocked me. Suddenly, it showed that he was calling again. I answered and said hello, asking who it was. He said he was Muhammad, I think, so I asked who again. He said Abu so-and-so because I didn't recognize him. I asked why the number was wrong, and he kept joking around. I went to block him, but he kept calling me every now and then, and I don't know what to do.