TUCoPS :: Phreaking Technical System Info :: lnenoise.txt

Trunking System Line Noise

Written by Bill Noel

Your system has noise!!  Ever heard that from one of your users?  Of
course you have.  And did you have a problem?  Most likely not.  If you
had a noisy line then all of your calls would have been noisy.  Then
where is the problem?  It is in what is known as the trunking network.
The Trunking Network is a series of lines and trunks that connect
switching offices.  All offices do not have direct trunks, so they are
routed through a connection office.  Sometimes these trunks operate on
copper cable, sometimes onT-Carrier, and sometimes on the Fiber Optic
cables that are currently being installed.  Any one of these methods can
cause data problems.  In fact, any carrier system can cause one way data
errors.  That is, the BBS can be seeing errors and the user does not see
them, or vice versa.  The latter problem makes your user know for sure
that your BBS is in trouble.

Trunking Network problems are the most difficult problems to solve.
Southern Bell does not train their Repair Clerks to handle trunking
complaints.  What you should do when you experience data problems to a
certain exchange is listen to a quiet line into that office.  Try to
describe the problem in terms of steady noise, "popping," "frying,"
"other people on the line", etc.  Tell the repair clerk that you always
have this type of problem when calling the 457 exchange when calling
from the 999 exchange.  Tell her this is a trunking problem and to
please really the report to Trunking Maintenance.  Never tell her that
you have a data problem.  Southern Bell does not guarantee data
transmission on non-conditioned lines.  (However, a non-conditioned line
that meets all of their normal residential service requirements will
support data up to 2400 baud with very little problems).  Remember that
when you buy a cheap modem, you get a cheap modem.  Why was it cheap?
Because they left things out like noise filters!  Keep that in mind when
you buy.

But what if you are really having trouble on you line?  Be careful
before calling Ma Bell with a complaint.  If you are not paying them the
$1.00 service charge for House Wire Maintenance, they will hit you with
about $35.00 per hour to fix the problem, or even if they don't fix it
but prove it was you fault.  The mini-jacks located in your house can
cause you a lot of noise problems.  They get all kind of things in them
like smoke, grease, animal hair, and dust.  These things cause the
contacts to corrode.  Corrosion causes noise.  If you have an OHM meter
and the technical skill to use it, lift the house wire from the
terminals and check for high resistance shorts in you house with all of
your modems and phones removed from the jacks.

Noise problems can also come from the carbon blocks located in the small
grey box located where the phone lines enter your house.  Normally this
condition will appear after an electrical storm or high winds when there
may have been currents flowing on the phone lines.  These devices belong
to the phone company and you should not mess with them.
I hope this will shed some light on the subject of noise for you.

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