View Full Version : How many wire required for a phone line?!

21-09-2010, 08:42 AM
I know nothing about phone wiring requirements and need a bit of guidance on a little project to install broadband into a building.
The building has secure data lines for the occupiers but our community group needs a phone line to enable us to install a totally separate broadband connection.
How many cores are required for a phone line? Two?

21-09-2010, 08:46 AM
Two cores arranged in a twisted pair of cat3 or better is required for a standard phone line.


21-09-2010, 02:45 PM
Two cores arranged in a twisted pair of cat3 or better is required for a standard phone line.



In the US - we have usually 4-to 6-twisted pairs in a common sheath for our standard 'copper' for telephone service. It can suffice for DSL if the D-SLAM is close enough.

The pairs are twisted at different revolutions-per-foot to achieve different attenuation of spurious RF or induced signals, and the installer takes the cleanest-sounding pair into the house from a hub outside - usually on a pedestal or a break-out box on the side of the house.

If DSL is to be installed, then a signal splitter is usually put inside the break-out or in the pedestal and from there we bring in CAT5e or better.

Is that about the same as there?

21-09-2010, 02:54 PM
In NZ the service lead into the house only has 2 pair. We skipped straight to the kids having cellphones rather than their own dedicated fixed lines :D

21-09-2010, 03:04 PM
Is that about the same as there?Yep, pretty much :D. The house feed is usually only one (more common) or two pairs though - one pair per phoneline. As most people only need one line, the second pair is usually disconnected.

21-09-2010, 03:05 PM
DSL is a good choice, and u can google the specific question. it is said that it required at least two wires.

21-09-2010, 03:07 PM
...it is said that it required at least two wires.That's correct - DSL is usually run over a standard single pair (two wires / cores) phoneline.

21-09-2010, 04:29 PM
Most of the copper in the US is really getting long in the tooth and failures of pairs or multiple pairs in the same sheath are common.

In San Jacinto where we lived before, we had the standard 6-pair and they could only find one leg in one pair that could hold the ring 100% of the time and another leg in a different pair that was good 80% of the ring.

That's pretty bad! The dielectric capacity was shot.

My DSL became ADSL and there was nothing I could get Verizon to do about it.

21-09-2010, 04:33 PM
2 wires now but a few years ago it was three wires one was an anti tinkle line.
I changed my 3 wire house wiring to 2 wire but it actually made no difference to speed or quality.