Date   : Sun, 21 Mar 2010 11:45:08 +0000
From   : darren.grant@... (Darren Grant)
Subject: [OT] ADSL capabilities

On 21 Mar 2010, at 11:04, John wrote:

> 
> 
> I believe this will work, but only if you use modern phones - older phones
> on the extension wiring may not ring if you disconnect the bell wire.
> 

There is a lot of misinformation out on the net and this I'm afraid is one
of them.

Every telephone device that is connected to an ADSL enabled line must have 
a filter in place. The extra ring signal generated by the master socket 
is therefore not used as the ring signal is not passed through a microfilter.
Every microfilter connects to the line with only 2 wires and then contains
its own ring capacitor, to generate a clean ring signal for the phone.

So in summary..

A line that has no ADSL and therefore no filters should have the ring wire
connected to all extensions as not all phones will ring without it, especially
older ones.

A line being used for ADSL with microfilters has no need for the ring signal 
as it is not used by any telephone equipment, it just serves to cause an
imbalance in the ADSL signal causing quite a lot of signal degradation in
most cases. The ring signal is instead generated by the capacitor included
in every microfilter.

A line being used for ADSL with a filtered faceplate should have all 3 wires
connected from the faceplate as microfilters will not be necessary and a
clean (post-filter) ring signal is provided by the ADSL faceplate.

In case anyone is wondering this is my area of expertise so I somewhat despair
at the way there is so much misinformation on the internet about the subject,
so felt compelled to respond, nothing personal against you John.