Guy harassing my sister by spamming her with calls.

A random guy is spam calling my sister since yesterday. He called her and asked "kana mandira galani?" then she goes "Who is it ? Do I know you?" and he says "na janini but chinha jana heijiba" she scolded him and cut the call. When she told me about this incident I called him and scolded him like anything. He got shit scared and said "sorry bhai number delete karidauchi au karibini". But se ete jananku call kariki harass karuchi je taa truecaller re only spam reports hi achi. Se janiparilani mu kaha pain call karithili. That's his number - 8260463800. (Over 93 spam reports) and comments re bohut jhia creep kahichanti. What can I do ?

Update - He had called me and asked for forgiveness and pledged to not repeat the same mistake again. His family members were worried about him. That was something which made me sad. Thank you all of you for your kind support (esp those two of you who posed as a lawyer and a cop LMAO). Lots of women won't have to worry nomore cause of you guys. I request all of you to not bother him anymore since we've made someone realise what sort of crime he had gotten himself into. Thank you from the bottom of my heart. I was so worried about her as she is too naive, lives in CTC where she has no one around to look after her. Love you all.