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 --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]