Re: The FIREWALL CHIP. U're phone always offhook?
You wrote:
We have potential bugging devices in all our houses - The telephone! Of course, when it is onhook, the microphone does not transmit... or does it?
The Mondo article ("Total Surveillance" by Charles Ostman) was a joke.
From the innacuracies in what I do know about, I assume all of the phone-paranoia is also unjustified.
Actually, there is a germ of truth in this. On older phones (don't know if this works on newer electronic phones) when the handset is 'on-hook' a switch opens and breaks the voice circuit. This of course only works for DC circuits. If you drive that same circuit with an AC signal (from further up the line) then that 'open' switch becomes a capacitor and acts as a band-pass filter. Signals from the mic will then modulate that AC current and can be extracted and reconstructed. Supposedly the Dutch police have perfected this and use it in investigations to circumvent legal restrictions on physically bugging suspects homes; or so was alleged a couple of years ago during a narcotics trial in Amsterdam. Dale H.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SANDY SANDFORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C'punks, On Thu, 2 Feb 1995, Dale Harrison wrote:
. . . Actually, there is a germ of truth in this. On older phones (don't know if this works on newer electronic phones) when the handset is 'on-hook' a switch opens and breaks the voice circuit. This of course only works for DC circuits. If you drive that same circuit with an AC signal . . .
There's another angle I may have mentioned before. Many electronic phones come with a ``feature'' that allows you to call home, produce an electronic tone and eavesdrop on your own house. When the tone is sounded, the ringing stops (or never starts) and the phone goes into ``off hook'' mode (i.e., the microphone in the mouthpiece is turned on). Even if you did not buy this feature when you bought your phone, it is still there, just waiting for that electronic tone. You can't produce it, because you didn't buy the doohickey, but anyone with such a doohickey can call your house and listen in. . . S a n d y ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From a couple of folx....
Actually, there is a germ of truth in this. On older phones (don't know if this works on newer electronic phones) when the handset is 'on-hook' a switch opens and breaks the voice circuit. This of course only works for DC circuits. If you drive that same circuit with an AC signal . . .
There's another angle I may have mentioned before. Many electronic phones come with a ``feature'' that allows you to call home, produce an electronic tone and eavesdrop on your own house. When the tone is sounded, the ringing stops (or never starts) and the phone goes into ``off hook'' mode (i.e., the microphone in the mouthpiece is turned on).
[ Snip! ] A simpler solution is to keep the phone in another room used mainly for phonecalls, or even in a small office if you don't make an sounds there worth evesdropping on. (The really paranoid can soundproof/tempest-proof the room....)
participants (3)
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daleh＠ix.netcom.com -
Robert Rothenburg Walking-Owl -
Sandy Sandfort