The recipient of the call usually hears a loud and random noise when they answer the phone, and if they do not hang up and the caller remains unaware, will sometimes receive information the caller would rather not disclose.
The recipient of the call typically hears random background noise when they answer the phone. Also, if they do not hang up (or the call is answered by voice mail) and the caller remains unaware, the listener will sometimes "overhear" (or record) information the caller would rather not disclose.