Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!texbell!vector!telecom-gateway
From: john@zygot.ati.com (John Higdon)
Newsgroups: comp.dcom.telecom
Subject: Re: Some Comments On The GTE "Problem" in California
Message-ID: 
Date: 23 Sep 89 04:53:54 GMT
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In article , zorch.SF-Bay.ORG!scott@
cs.utexas.edu (Scott Hazen Mueller) writes:

> I'm not picking on John, really I'm not; his was just a good example.  I
> read the the words, but I'm seriously lacking some referents.  For instance,
> "subscriber carrier"?

When the phone company runs out of pairs and there are more lines that
need to be installed, subscriber carrier allows two subscribers to use
one physical pair of wires. At the CO (or wherever it is necessary to
channel two services into one pair) a carrier unit is installed and a
matching unit at the "carrier" customer's location. The unit
superimposes 30-60 KHz carriers on the line which carries the voice
and supervisory signals. The "metallic" customer is the one using the
line in the conventional manner with a conventional instrument, while
the "carrier" customer has his service out of a "subscriber carrier"
unit.

> The description implies a  generator on
> John's premises, which was powered from the phone system, and which he
> added a power supply to when GTE switched it off.

Yes, the unit is on the premises. It has a nicad which trickle charges
off the DC on the phone line when the line is not in use by either
party. The ring current, talk battery, and carrier encoding/decoding
are all powered by that nicad. If the phone is used a lot, or for some
reason that DC is not present, eventually the carrier subscriber's
phone may not ring or even pull dial tone. Fortunately, there is a
place inside the unit where one can hook up a 15V transformer and the
unit then becomes independent of the DC on the line.

> Also, his line was "converted to metallic"?

Eventually, they had enough cable pairs in the area (by installing new
cable) to give me one all to myself.

> What was it before it was metallic - a piece of string with two tin cans?

No. That probably would have worked better.

        John Higdon         |   P. O. Box 7648   |   +1 408 723 1395
    john@zygot.ati.com      | San Jose, CA 95150 |       M o o !