On Sun, 3 Dec 2006 20:26:07 -0500
Thor Lancelot Simon <[EMAIL PROTECTED]> wrote:

> On Sat, Dec 02, 2006 at 05:15:02PM -0500, John Ioannidis wrote:
> > On Sat, Dec 02, 2006 at 10:21:57AM -0500, Perry E. Metzger wrote:
> > > 
> > > Quoting:
> > > 
> > >    The FBI appears to have begun using a novel form of electronic
> > >    surveillance in criminal investigations: remotely activating a
> > >    mobile phone's microphone and using it to eavesdrop on nearby
> > >    conversations.
> > 
> > Not very novel; ISDN phones, all sorts of digital-PBX phones, and
> > now VoIP phones, have this "feature" (in the sense that, since
> > there is no physical on-hook switch (except for the phones in
> > Sandia and other such places), it's the PBX that controls whether
> > the mike goes on or not).
> It's been a while since I built ISDN equipment but I do not think this
> is correct: can you show me how, exactly, one uses Q.931 to instruct
> the other endpoint to go off-hook?
I don't recall if it's Q.931 per se, as much as the CO.  Or rather, I
know for certain that various government security agencies were quite
unhappy about ISDN phones with speakerphone capability being deployed
in sensitive sites.  The speaker button was not, as I understood it, a
hard button; it was a soft button that the switch responded to.

                --Steve Bellovin, http://www.cs.columbia.edu/~smb

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