Home page logo

nanog logo nanog mailing list archives

Re: DSL line stealing when there is no tone - DANGER - Operational content
From: Steve Schaefer <schaefer () simone dashbit com>
Date: Wed, 16 May 2001 13:10:11 -0700 (PDT)

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

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.

On Mon, 14 May 2001, Alex Bligh wrote:

as for relibility, I cant tell you the number of times a Verizon tech,
would be out to install a phone line and steal one of our dsl lines cuase
it did not have a tone.

As a (serious) question, why not stick a tone on it? How much
can an oscillator at the CO plus some trivial passive low pass
filters (one set per line), cost? (Or, if you aren't the DLEC,
stick it at cust prem). Just don't use the trace tone... (translation
to US terminology may be required)

Alex Bligh
Personal Capacity

  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]