OT: Ethernet/Telephone cabling

[dsr at tao.merseine.nu]

On Fri, Jul 23, 2004 at 04:28:55PM -0400, David Backeberg wrote:
> You can google for the pinout of a typical ethernet cable. There are only four 
> wires used, but if you tried using six of those conductors you might get some 
> crosstalk. I imagine the four wires that aren't used are done intentionally 
> to preserve signal quality.
> 
> On Friday 23 July 2004 16:18, Robert La Ferla wrote:
> > I purchased a new house that has each room pre-wired with CAT-5 jacks.
> > All the cables meet in the basement but there are no connectors on
> > them.  These same cables are also used for telephone.  Each cable has 8
> > conductors (in 4 twisted pairs).  One twisted pair (or 2 conductors) is
> > used for telephone leaving 6 conductors (3 twisted pairs) free.  My
> > question is can I have both telephone and Ethernet on the same cable?
> > If so, what speed?  Do I have other options like some sort of Ethernet
> > telephone?

First off, remember that Cat5 is a quality designation for the
cable itself. Is it marked Category 5? or 3? 

Second, the original ethernet spec specifically reserved one
pair for voice connections. Since you aren't running a data
center, I wouldn't have many worries about running phone on one
of the extra pairs, even next to a 100Mbit connection.

You also have the option of using a VOIP (voice-over-IP)
terminal, which may or may not have a phone handset built in.
(If it doesn't, it connects up to your own phone.) These are
being sold for reasonably low fees when purchased along with a
local-and-long-distance voice plan (see www.vonage.com, among
others) or you can buy used units off of EBay. (The cisco
ATA-186 is pretty common.)

In the basement, your best bet is to feed the cables into a
punchdown block, and from there into a patch panel. Then decide
what you want to do: add POTS connectivity, an ethernet switch,
whatever.

-dsr-