While we might imagine the FBI, CIA or NSA listening in on our phone conversations, the reality is that tapping a phone line is relatively easy for a business competitor or jealous spouse as well. So whomever you suspect is listening, I suspect you’d like to put an end to it.
University of Pennsylvania computer science professor Matt Blaze Âdissected the wiretap equipment commonly used by law enforcement and found a few, um, bugs. Spies, it turns out, don’t like to record dead air, so they turn the system off by playing a special C-pitched tone when the target phone is hung up. As a result, anyone with an MP3 player and a recorded C can prevent eavesdroppers from snooping on their private chatter.
You can download Blaze’s C tone here and broadcast it at low volume during phone calls. Not foolproof, but it’s one more tool in your privacy toolbox.
Via Wired.