"Interrogator": "Who did Karan initially assume was calling, and how did the caller respond when Karan expressed his suspicion that it might be a prank call?", 
"Interrogee": "So, Karan thought that it was his friend, he was pranking. So he thought it was his friend Rahul and he confessed to the caller that if it is his friend Rahul, and the caller said, No. But I also know about Rahul and he also a drug addict like you."