Voice over data

17 Dec 2003

      Eric Hughes wrote:
...
the great voice-over-data protocols and products introduced by
   Intel, Rockwell, ZyXEL and others at Comdex which will make
   Voice-PGP so much easier
As I understand these voice-over-data products, the voice goes over
analog, added to the modem signal.  The modem signal is interpreted,
and then reconstructed and subtracted from the incoming signal,
leaving voice.  Very clever, but insufficient for secure phones.
I don't think that's how they do it. As far as I know, most methods multiplex
digitized audio with the data. One system used by some people in India provides
a dynamic combination of fax, (digitized) voice and data, depending on the
throughput - eg vox/9.6 data if 14.4kbps, fax as well if 19.2, etc.

While Intel and others are proposing standards, ZyXEL does it with software
along with a voice card or possibly RJ11 input. A friend of mine saw a demo
of it at Comdex, on an old 1496E (16.8 kbps zyxel to zyxel). The new v.34 does
28.8k - lots of room for clear digitized voice and high speed data.

This is exactly why I thought it would make secure voice easier, if not secure
phones (who wants to lug a modem and PC around as a 'handset'?).

I'll be testing some Onetics Rad VFAST modems this week, which apparently do
digitized voice over v.34 as well.

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