In the name of security, the National Security Agency (NSA) has become pretty lenient with what they consider "privacy." To be fair, we live in an age where people tend to share every ounce of their lives online without prompting, so it doesn't really make their jobs all that hard.
Still, it's pretty widely believed that the government (or talented hackers) can listen in on your phone calls. Even many social media apps request permission to use your microphone, which gives them that permission to technically tune in whenever they want. Basically, if Mark Zuckerberg is taking steps to protect himself from spies, you may want to consider doing the same.
Perhaps no one knows better about protecting yourself from government spies than Edward Snowden, who famously leaked classified NSA information back in 2013. The government has wanted this former CIA employee arrested for a long time but he's been granted asylum in Russia for the moment. Needless to say, he knows a thing or two about protecting his privacy.
Snowden has created the ultimate smartphone privacy monitoring case (or at least outlined the plans for its creation). Though the design itself is specifically created for an iPhone 6, the core elements behind it can be easily tweaked to fit any smartphone design.
Snowden didn't create this concept on his own. He had help from prominent and talented hardware hacker Andrew “Bunnie” Huang. Together they've created what they believe to be a comprehensive yet compact device to essentially get "off the grid" no matter where in "the grid" you are.
The case will basically plug into the hardware of your smartphone through a SIM card and monitor the phone's circuit board. From there, it will be able to tell you if at any point your phone is transmitting or receiving signals you're unaware of.
While not everyone may feel the need to protect themselves from the powers that be, this device could be especially useful for high-profile targets like journalists who are secretly embedded in dangerous areas in order to get to the truth of a story. Putting your phone in airplane mode (or even "off") doesn't guarantee that it can't still be used as a monitoring device.
Interestingly, the collaborators (Snowden and Huang) have never met face-to-face. They trust each other through reputation only and communicate through an encrypted communications app. They've already tested early phases of the protected phone and believe their new model could be really useful for anyone interested in truly protecting their privacy.
While both men have insisted that their case is specifically designed with journalist safety and protection from foreign governments in mind (rather than the NSA), it could theoretically be used by the general public. Snowden hasn't used a wireless device or owned a smartphone since his famous move against the NSA in 2013.
With the introduction of this revolutionary device and its "introspection engine" that alerts you of what is actually happening with your phone, all of our lives could change significantly. You could rest assured that if people want to watch or listen to you, they're going to have to get a bit more creative about it.