One prank extinguished the flame of friendship

I was not in happy mood. It seemed like still pain had not settled down. Conditions are not in my favour. I thought I would talk to my best friend today. We were talking that then an unknown call I received but he said ,"tumhara baap bol rha hoon" in loud sound . Oh my god I scared badly because my father was at home. Who is he ? It was very terrible to me after all I didn't know who is he. Lots of messages suddenly started coming from an unknown number and yes it was that number which was used to call me .In messege I saw he said that call me and then I will introduce myself to uhh. Nobody had ever talked to me like this before. It was about 10 o' clock in the night. There was not even much relaxation in my house that I could receive someone's call at any time. So I messaged the number to my best friend and said, know who he is. Threatening me to that when you come to college then tell you who I am. After sometime my friend messaged me and said he cut the call of mine without response. Repeated messages were coming from that unknown number. Even I called once, but no one spoke on the call. It was getting late at night and it seemed as he was enjoying it by making me scared. At that time, my friends also suspected.Whatever message I was sending to my friend, he (unknown no.)was sending me. It seemed as my mobile had been hacked. Finally I got upset and told this at home. We treat him like cybercrime, he has already told that he is my best friend with whom I was talking and asking for help.

Nothing we did against him because he was just enjoying. He was kidding. He did not hack anything. But yes it is true he had lost his life long friendship .
Prank is necessary to make life happier but not this type. Eventually this incident killed off a beautiful friendship relationship.