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Re: [OM] OT: Telephone Snooping

Subject: Re: [OM] OT: Telephone Snooping
From: Chris Trask <christrask@xxxxxxxxxxxxx>
Date: Tue, 21 Jul 2015 14:18:28 -0700 (GMT-07:00)
>
>The short answer is "yes and no". Just because you are paranoid doesn't
>mean that they aren't out to get you.
>
>The phone switches are designed to allow for government listening in. But
>only of calls, not the room ambient between calls.
>
>However, there are a few technological exceptions worth considering.  Any
>cellphone or IP phone can be remotely enabled and put into a listen mode.
>There are apps for that. As there is no physical or electrical barrier from
>outside to inside you are vulnerable to outside activation.
>

     I dragged out a large British 2-volume text on telephony, and I think I 
can see how this works.  If the microphone (voice coil) is attached to the 
centre tap of the system side (subscriber line) of the hybrid coil, you can 
still listen to the microphone as that part of the 2-way system is common-mode, 
and all that the snooper has to do is access the common-mode side without 
ringing.  The earpiece (speaker) on the odd-mode side of the hybrid coil is 
shorted by the cradle hanger switch.

     Seems you should be able to defeat this by opening the connection between 
the microphone and ground with the cradle switch.

Chris

When the going gets weird, the weird turn pro 
     - Hunter S. Thompson
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