Message from discussion DACS 3

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From: b...@dsl.co.uk (Brian {Hamilton Kelly})
Newsgroups: uk.telecom
Subject: Re: DACS 3
Date: Mon, 13 Aug 2001 21:03:00 GMT
Organization: Dragonhill Systems Ltd
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In article <MPG.15e234ef5979d9a8989...@news.demon.co.uk>
           t...@tbl.demon.co.uk "TBL" writes:

> Did you know that the current DACS service (the one which people complain 
> about due to it's non-compliance with V.90 modems) is actually DACS2?

Yes.

> DACS1 was originally deployed in the early to mid 90's, with the current 
> DACS2 system being brought in due to the originals failure to operate 
> with certain Select Services, the main one being Caller Display.

It was also brought in because the original DACS, being designed at a
time before V.32 was widely deployed, let alone V.34[bis], wasn't very
kind to modems or faxen.  (I rather think that the CLID modification was
a variant on the DACS2, either the second or third generation thereof: of
course, there were places that needed the second or third implementation
of DACS2 because they wouldn't work with the short "exchange line" from
the DACS box, this particularly applied to some fax machines and TAMs.)

> DACS2 began to be installed at significant volumes in 1995, before the 
> V.90 standard took off.

Correct; in 1995, the V.34 standard had only been widely available for a
few months, and 33600 wasn't generally available until 1997.  As for the
concept of being able to achieve ANYTHING faster than 33k6, the idea was
risible and no one even imagined it could ever come to pass, let alone
within only about four years.  I wonder if V.90 surprised Claud Shannon
before he died recently?

> This then means that the current discussions about the fully digital V.90 
> compliant DACS system, would actually be called DACS3

Correct; ISTR Phil K having made reference to such a beastie.

But anyone who's been reading this group for more than a year or so
already knew all that, so why did you post?  (Those who /didn't/ know
should, of course, have been conducting research at DejaGoo.)

-- 
Brian {Hamilton Kelly}                                          b...@dsl.co.uk
    "We have gone from a world of concentrated knowledge and wisdom to one of
    distributed ignorance.  And we know and understand less while being incr-
    easingly capable."              Prof. Peter Cochrane, formerly of BT Labs