Current phone lines only use two wires.  Most connecting wires from the
wall jack to the telephone equipment have four wires but only two of them
will work with normal telephone equipment including modems.  This is
because normal telephone equipment only connects to one pair of wires in
the connecting cable, the red wire and the green wire.  If you have a
telephone or modem that will switch between two different telephone lines,
then all four wires will be used, one pair for each telephone line.

If you remove the cover from a wall jack, you should see two pairs of
wires, a red/green pair and a yellow/black pair.  With a one-outlet wall
jack, all four wires will probably be connected to the outlet to allow
using both lines with telephone equipment that can switch between the two
lines.  With a dual-outlet wall jack, one pair of wires will be connected
to each outlet.  If your internal wiring is connected as it should be, the
red/green pair is your primary telephone line and the yellow/black pair is
your secondary telephone line, if you have one.

You can prove these claims by switching the red/green wires with the
yellow/black wires.  If you have two phone lines, doing this will switch
the phone from one line to the other.  If you do not have two phone lines,
your phone will no longer work because it is now connected to the
non-existent secondary line.  Or you could simply disconnect the two wires
that are connected to the "yellow/black" connections (they should be
marked) on the wall jack.  This should have no effect on the telephone
working.

----------
> From: Patrick C Black <[log in to unmask]>
> Subject: Re: [PCBUILD] Modem Connection Speed Prob.
> Date: Tuesday, July 21, 1998 12:46 PM
>
> Not only did you prove me wrong, i just proved my self wrong.  I got the
> same performance. Of course this is a BBS where I download one file at a
> time,
> I'm not sure about the Internet (which i dont have).
>