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Re: DSL line stealing when there is no tone - DANGER - Operational content
From: Daniel Senie <dts () senie com>
Date: Wed, 16 May 2001 17:14:35 -0400


At 04:46 PM 5/16/01, Greg Maxwell wrote:

On Wed, 16 May 2001, Steve Schaefer wrote:

> The main reason not to stick a tone on the DSL line is that the line
> coding (2B1Q) used by SDSL uses the baseband (low frequency part of the
> spectrum).
>
> For line codings that don't use the baseband (CAP, DMT and variants like
> G.lite), the DSLAM (telco central office DSL equipment) is always set up
> so that the DSL can be combined with a voice circuit over the same pair,
> so it still doesn't put a tone on the line.

I predict great profits for the first person to duct tape 100 'tracer
tone-generators' into a 23 inch rack with 48v DC power source.

Better: a chip with a recorded voice: "This pair is in use" interspersed with a tone.

While present baseband signalling may be unable to handle such, it'd be useful if future ones purposely avoided the zero to 5kHz spectrum to allow for such a mechanism. Clearly the telco workers have demonstrated the absolute necessity for such a facility.
-----------------------------------------------------------------
Daniel Senie                                        dts () senie com
Amaranth Networks Inc.                    http://www.amaranth.com



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