> In my youth, I dug trenches as a contractor for a phone company
> and put down a bundle of 4 pvc pipes about 2" in diameter each
> for fiber optic lines.  My guess is that a lot of the phone line
> traffic is moving over fiber without the lossy effects of copper
>
> - next question is how they transition from fiber to copper,
> and I don't have a clue.

As I recall, fiber optic cable runs from the central office to
a SLIC (Subscriber Line Interface Circuit, Concentrator, etc).
SLIC is remote box that is installed in a neighborhood.  It is
"owned" by the CO switching center.  Fanout is copper pairs to
the houses in that area.

So DSL line limitations (18 kilofeet from memory) is from SLIC
to subscriber premises.

> The bigger question to me is how the phone wiring is laid out
> vs. cable.  Once upon a time I suppose you had one pair of wires 
> between your house and the pbx, but surely that's not possible now.  

In a lot of cases, that's still how it happens.  Newer areas, the
copper pairs run from premises to SLIC's copper interface.

Rural areas have _much_ longer runs of plain copper back to some
device that looks like part of a CO phone switch.

						Lee Jones

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