From: Robert Rothenburg Walking-Owl <rrothenb@ic.sunysb.edu>
Date: Fri, 3 Feb 95 14:00:10 PST
To: sandfort@crl.com (Sandy Sandfort)
Subject: Re: The FIREWALL CHIP. U're phone always offhook?
In-Reply-To: <Pine.SUN.3.91.950203103828.3246E-100000@crl.crl.com>
Message-ID: <199502032159.QAA12943@libws4.ic.sunysb.edu>
MIME-Version: 1.0
Content-Type: text/plain


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....)