You are almost correct. On a regular phone the CO test there line to see if
it has a short or open on the line. No loopback. They can tell if there is a
load or not. If you draw to much current the line thinks it an off hook
condition. It then provides dial tone
 Some pay phone and CO 2 wire trunks use a momentary ground on one side of
the line to bring up the dial tone once you gave gone off hook. That's about
it for a 2 wire phone line. I'm not up on DSL.
Larry Taylor  KF6JBG Telecomm
----- Original Message -----
From: "Bob Ammerman" <rammerman@ADELPHIA.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, September 23, 2003 6:52 AM
Subject: Re: [PIC:] Stealing power from the phone line update


So, if I understand you correctly:

For residential installations the telco generally have one pair hard copper
directly from the CO to the home. They have a loopback/isolator at the CO,
and a lightning arrester at the demarc. And that is all.

No wonder I never saw one.

Bob Ammerman
RAm Systems

(Taylor)I Deleted the rest!!

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