Ruling on making calls from the central exchange without the knowledge of the parties concerned

Question: I know a relative of mine who works in one of the departments of the central exchange, and he transfers some international calls to me for free without the knowledge of the parties involved. Is there any sin on me for this, even though the phone owners are wealthy people?

Answer: This work is not permissible except with their permission, and it is a betrayal by your relative. We ask Allah for guidance for us, for you, and for him.