Several years ago, a coworker who knew about voice processing set up a device at his house that when you called his number, it would answer with whale song. Th

Several years ago, a coworker who knew about voice processing set up a device at his house that when you called his number, it would answer with whale song. This had just enough entropy to make a robocall believe that there was someone there. It would keep the robocalls going for quite some time. If you wanted to reach him, you had to dial an extension.