Disabling your cell phone’s mic for security


[Dan] set up this simple cell phone hack to disable his microphone when he’s not using his cell phone. He had read that the government can listen to you using your cell phone, even when it is off. This concerned him enough to hack into his phone. He removed the expansion port and wired the microphone to a magnetic reed switch. A strong magnet located in the screen side of his flip phone opens the circuit when he closes the phone. He notes that you could always just pop the battery out of your phone, but then you are left completely disconnected. This mod allows you to still receive phone calls.

115 thoughts on “Disabling your cell phone’s mic for security

  1. To those who suggest monitoring the antenna.

    If I were designing a phone that had the capabilities to listen in on conversations, I’d have it run passively all the time and dump the detected audio in some memory, then send it all out when the phone is on.

  2. Wow!

    Hack a Day must need some banner ad hits…

    That NSA wiretapping story was highly sensationalized. There is no need for a warrant to tap a non-U.S. citizen. Canada and France listen to U.S. citizens all the time (to steal our secrets).

    Also, McCarthy was right. Read about the VENONA project for more info on that.

    Also, you idiots should remember that victims have rights too…

  3. “That NSA wiretapping story was highly sensationalized. There is no need for a warrant to tap a non-U.S. citizen. Canada and France listen to U.S. citizens all the time (to steal our secrets).”

    Bingo. When the story first broke (and each subsequent revival of it), I spoke loudly and clearly into my closed flip phone… saying “Allah Akbar! I shall fly the plane into the Sears Tower for Muhammed!” and I’ve yet to get any visits.

    I figure if they’re watching me, recording everything I say and do, I’ll do my best to poison the data they have.

    Or maybe some people can just get over themselves and stop using paranoia as an excuse to fuel their narcissism.

  4. This is a good idea for a laptop: When you close the lid, the wi-fi turns off. You might want to be able to disable this function, but in public places I think it would add a level of security.

    Go ahead and say it: “Paranoid freak! A hacker can already get into your computer if they want, there’s no reason for adding any layer of security!”

  5. Cool hack, interesting idea, but the bottom line is if you’re in deep enough that they’re listening to your cellphone, you probably shouldn’t be using a cellphone anyway (or just use disposable phones and cycle them often).

  6. “That NSA wiretapping story was highly sensationalized. There is no need for a warrant to tap a non-U.S. citizen. Canada and France listen to U.S. citizens all the time (to steal our secrets).”

    Seriously? You believe that? The constitution protects EVERYONE in the US equally (take that as you will) wheter they are citizens or not. As to the Canada/France nonsense… I don’t even know how to address that other than to ask: how do you figure that’s possible, let alone likely? Get a grip!

  7. @Jamesmaddy: You must of missed the comment from Dan above,
    “OK, people who think I am paranoid are missing the point. If I was paranoid I never would have put this up on my web page, would I? My point was that if people get in the habit of just shrugging their shoulders to such things then we are in big trouble.”
    Meaning his intention wasn’t to become more private.

    But nice way to attack some guy that shared a cool hack with us all.

  8. The suggestion that “the government” can listen to your phone is ridiculous. Try this test:

    Make a call, put your phone near a common FM Radio – listen to the interference created by the outgoing signal.

    Now end the call and leave your phone near the Radio… any outgoing signal?

    Ok. Now you know.

    Your phone MUST send out a signal for someone on the other end to HEAR you. Try the same test and MUTE your mic whilst in the call. Notice the drop in signal strength – because you aren’t transmitting as much signal – just a ping to the tower to keep the line open.

    I live in a country with a relatively small population, but there would easily be 10 million + mobile phones in use. As a government – are you going to listen to the average Joe chatting with his girlfriend?

    Meh. You’re just not that important – sorry.

  9. Even if you think this guy is paranoid, this hack has legitimate uses — I’ve picked up my phone several times, just to find out that my girlfriend “butt-dialed” me.

    I’m sure there are people that you don’t want to hear your drunken antics; like your parents.

  10. Again, forget the government.

    This type of listening, and GPS tracking, are available as commercial subscription services so that parents can listen in on the kids and jealous boy/girlfriends can keep tabs on their s.o.’s. Lots of other reasons, too.

    I guarantee almost everyone falls under one of THOSE circumstances at least once in their life, except of course for the basement dwellers attacking this guy. They don’t get out much or get dates anyway, so to them it probably really is a useless hack.

  11. The people who want to do this to protect themselves from the government are wackos.

    The people who want to do this to protect themselves from people significant others or other people they know need to (1) learn how to build relationships based on trust, and (2) learn accept the consequences of your mistakes rather than try to cover them up.

    Either way, if you somehow feel that you need this hack, you are pathetic.

  12. Every fascist knows it is better to instill fear — than actually monitor the proletariat.

    “They” don’t care what you think as you will perform as instructed.

    This is why you don’t like your job and hate your life.

  13. well, i Think He brings up some Exciting points. Can you honestly say you want the government listening in on you? And granted, yes; they probably have little reason to. but, shouldn’t Knowing that they can concern you Even a little bit? I for one think Such an Abuse of communication by our government is something we should no Longer stand for. but, I guess this is just my two cents. well, have a good day Everyone.

  14. Muscles? Use them or lose them.

    Brains? Use them or lose them.

    Rights? Use them or lose them.

    If they have just cause, all they need to do is go to a judge who will give them a warrant and the phone company will let them do anything they want. But it turns out some elements of the government don’t follow the law. They spy not on Saudi Terrorists or Chinese Moles but on US citizens that object to being ripped off and sold out in clear violation of the Constitution. They are the are criminals.

    Do you know why the government hated Mitnick so much? Because when he broke into to Shimomura’s computer he found the source code that proved the NSA had developed mobile spy at will software before 1995 – long before 9/11. And, BTW, Mitnick’s ex-wife ratted him out, that’s the real way he was caught.


    Even tho your looser lives aint worth monitored by the Government or some other party, many hackadayers indeed are involved in breaking the law, politics etc. which makes this hack pretty useful.

    So nolifes sitting @ home STFU

  16. All you people bringing up the tinfoil hat stuff are the ones in the wrong here. The government in fact does have the ability to listen in on your phone — with a soft wiretap. You’d notice it because your battery life would diminish drastically as you’re basically on a call at all times. It’s been done — in mafia cases. Something tells me that if you need to read Hack a Day to get tips on beating the feds then disabling the mic on your cellphone is not going to be enough, though.

  17. “This mod allows you to still receive phone calls.”

    Err.. if you turn off your phone (as said earlier “even if the cell phone is off..”, how does that allow you to receive phone calls? Thus if you were going to do this, why not just pop out the battery? o.O

  18. Everyone who say this guy paranoid, think why you have firewall, why you use peer guard and why you dont just use qwerty for all you passwords ? Does you personality of any importance? Do uou have to hide something ? like those animal porn ?
    So you do want privacy online, but don’t care about it in real life ? WTF ?

  19. great hack!
    will do as soon as i get a reed switch.

    every ones a moron if they think the government isn’t listening in. they been in loop since the creation of telephone. anything government funded is going to be monitored. telephones, cellphones, internet, etc…. you named it they probably have they’re noses sniffing on it.

  20. I agree with those that think it’s very foolish to say “oh well” or “paranoid” about stuff like this. Even if you’re a law abiding citizen today who could care less if the gov listens in or not, will you be law abiding tomorrow? If bills like the Blair Holt Gun Licensing bill go through, i will not be inside the law cause there’s no way it’s anyones business how many guns I have. When will the gov take out a right that you strongly believe in and you decide to step outside the law? Most people are outside the law today and don’t even think about it (illegal/peer to peer downloading, etc.) the only difference is that the government won’t crack down on that like they will a terrorist threat for obvious reasons. But when will it be something they do crack down on and you’re caught with your mic on?

    This type of wiretapping is proven and has been used, therefore, it’s a great hack and an even better reason for doing it.

    all you others have fun putting full-trust in the hands of a bureaucrat and let us know how that goes.

  21. A better hack would be to install a piezo right next to the microphone and put it on the same circuit so it generates a noise/feedback when the mic is powered. That would notify the user that the black helicopters are coming and make it impossible for someone on the other end to hear anything over the noise. You could wire it into the flip sensor on a clamshell phone so the circuit is disabled when open.

    BTW, those of you who are paranoid and think that your phone will generate interference when next to a speaker/TV/radio… well that works for GSM/TDMA devices which are bursty (and their interference is why most are banned in hospitals). Spread spectrum phone (CDMA,CDMA2000,UMTS) signals appear as noise and do not cause interference.

  22. @Bob38: I like your idea using the piezo. You can get a reed switch with both a normally open and a normally closed contact. When in one position the phone would connect to the mic, and in the other position it would connect to the buzzer. When the phone tries to energize the mic it would sound the piezo. Unfortunately there is not much room available to work with. Another option would be to route a wire from the vibration motor, although I don’t know if the mic circuit would supply enough power for that.

  23. The problem is no matter how well-meaning, backdoors are found and abused.

    For example, the remote 3rd party control system put into telephone systems for law enforcement to catch the mob was subverted by hackers in Vegas to redirect calls for call girls to other companies less than 6 months after it was introduced. Hackers had mastered the system before local law enforcement even got training. Think about that for a while.

    [list of still active backdoors removed]

    If the government really wanted to help, they’d be designing better locks, not trying to cripple the ones we have.

  24. If you want to be safe from the government, all you have to do is speak in Arabic or Farsi. The military and three letter acronym guys apparently can’t find any straight translators (and they fire the gay ones).

  25. Or just do not have a cell phone and you will not have to worry about this, but if you must have a cell phone, One way around this is to use a handheld portable cell phone jammer that you turn on when not using your phone. This device is the size of a cell phone, but jams the signal of cell phones when they are not in use. Preventing your location from being tracked by triangulation, or conversations spied on. This device has a jamming radius of minumum of 10 Meters (30 Feet) and jams GSM/CDMA/ and GPS if needed. and has battery and can charge via car outlet or home outlet. I sell these for $90. You can get a jammer by contacting mail@ciotaenterprise.com

  26. The gov spying on you is fairly unlikely as they just do not have the man power to spy on everyone real time.

    Heck they have trouble monitoring suspected Al Queda members because they learned to swap sims regularly.

    Now corporate spying is a very big problem and a company that wants to spy on another company has a small target audience.

    As for software that’s laughable ever try to use a voice mail system that used voice recognition?
    They’re pain and it’s hilarious how inaccurate they are.
    Most places are now uninstalling them and going back to touch tone PBXs.

    Though it is possible to install spy software on a cell phone locking the damn file system like most phones do does make it harder to detect.

    As for using the speaker as a mic well it would be kinda hard as if it’s connected to a a DAC vs an ADC and there is no mixer circuit to switch the connections.
    Though some phones do use the speaker as a mic.

    If you work for a company with some IP that that would be valuable if stolen it’s not paranoia to check phones for taps , order untrusted devices powered down or have jammers installed.

    I think the triangulation and gps features in cell phones should be made user can disable it.

    As for accuracy triangulation is only accurate to around 3200 feet on average.

    So there is no need to worry about death by an orbiting laser.
    Heck they wouldn’t even be able to score a kill with a MOAB.

  27. nice hack but if you knew how shitty audio sounds coming from a cell phone you would have spent your time finding a bimbo w big tits instead of inhaling solder fumes
    seriously cell mics suck
    throw the friggin thing in a drawer and be done w it

  28. A less invasive “hack”:
    Take just the plug from a broken headset and plug it into the cellphone headset jack. Hell, even the correct size swizzle stick should disengage the internal mike and speaker.

  29. Paranoia can be useful sometimes. There are some cases every year when employers bug their employees “just in case”! If “common” (read: fucktarded) people wouldn’t be interested in bugging other people why is there a reasonably large market for bugs/miniature cameras and misc. wiretapping equipment? It’s not the government one should worry about.

  30. Nitori, you are so mis-informed. By saying “The government does not have enough manpower…” You really must be old fashioned. Old people do not understand the concept of modern technology. They do not have one person for every phone call. There are super computers that have enough processing power and speed to comprehend millions of conversations at one time. Research the NSA wiretapping scandal, Echelon, etc.. And the ATT whistle-blower who found an NSA communications splitter recording communications of all americans.

  31. People- Forget the govenment, this technology is available to anyone and everyone. All you need is the phone #, it is programmed remotely. Your phone will beep everytime they get a call/text. It’s real. It happened to me. Do a utube search and you’ll see many stories about on the subject. Nice work on the hack.

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