Unknown Caller - Harrasment

I had received a call on my Airtel mobile last month in June 2011 from the unknown caller (+919618192132) wherein he started talking with me using vulgar words about my sister. He was a male person. I then hung up the call. Later the same caller called me on my BSNL Landline on the same day which was a miss call. I have a Caller ID landline phone which showed me the caller's number which was same from which I got a call on my mobile.
This caller again called on our BSNL landine few days back and represented as if he was a friend of my sister and got her mobile number from one of my family member. Now this person is troubling my sister by calling on her mobile and harrasing her to be her friend. Request you to kindly help me out to identify the caller's name and address and perform a stringent action on him.