On Mon, 14 Sep 2009 21:41:14 +0100, Stephen wrote:

snip

If I add any more extensions is it worth using 3-pair/6-core cable or
can I save some money by buying the 2-par cable?



2-pair is fine for normal extension sockets. As almost all phones now
synthesize the bell signal internally the terminal 3 wire isn't needed
either! You can just use a single pair.

The only time that you need additional cores are when you have some types
of PABX on your system. Details for connecting these will come with the
PABX - there isn't a standard AFAIK. Wire 3 is the "Bell" wire and is
used to stop other phones "tinkling" as a dial phone dials a number. It's
just about always redundant now (even though it's officially still part
of the spec).

Manufacturers have to make their connectors suitable for all the systems
that are out there - and they are standard connectors now. That's why all
the terminals are provided.

Don't be tempted to mix ethernet pairs with telecom pairs in the same
cable. You'll probably find that it's part-functional, and very annoying
to debug! It's just not worth it for the cost saved.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.