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From: roy@alanine.phri.nyu.edu (Roy Smith)
Newsgroups: comp.dcom.telecom
Subject: Re: Basic Questions About Telephones
Message-ID: <10759@accuvax.nwu.edu>
Date: 12 Aug 90 14:31:31 GMT
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X-Telecom-Digest: Volume 10, Issue 563, Message 3 of 12


John Higdon writes (Vol 10, Issue 560, Message 2 of 3)

> The wire you describe, commonly called "D station wire" does not have the
> working pairs twisted [...] What you want is "E wire", where the pairs
> are individually twisted.

	The untwisted wire described is what I have always called
"quad station wire", I have no idea what the real name is, but I don't
think "D station wire" is right.  My AT&T catalog lists what they call
DIW, "D Inside Wire" which is indeed twisted pairs.  You can get it in
various pair counts from as few as 2 or 3 up to, I think, about 6 or
8.  The most common variety I've seen is 4 pair.  Unlike common 25
pair cables, the pairs are packed loosly in the PVC sheath, making it
very flexible.  It sounds exactly like what John is describing as "E
wire".

	I am willing to defer to hard evidence to the contrary, but I
have trouble believing you could get any appreciable amount of
crosstalk between two properly balanced circuits (even if not using
twisted pairs) over the, say, 100 feet of wire you might find in a
common residential installation.  My trailblazer coexists just fine
with my voice line over plain old quad wire, running what I would
guess is about 60 feet in the same quad.  In theory, I would agree,
you want to run twisted pairs if you have the choice, but if quad is
already in, I wouldn't bother replacing it for plain voice or
voice-grade modems.  


Roy Smith 
Public Health Research Institute
455 First Avenue, New York, NY 10016 
roy@alanine.phri.nyu.edu -OR-  {att,cmcl2,rutgers,hombre}!phri!roy