[Gllug] re: ADSL/telephone sockets

[Chris Bell]

On Mon 25 Oct, t.clarke wrote:
> 
> Personally, I found the following configuration at home works fine, even
> though not the approved master/secondary method:-
> 
> 
> Street===================Socket1============Socket2
>                            +                  +
>                          Microfilter        Microfiler
>                            +                 +      +
>                          Phone              Phone  ADSL
> 
> 
> Both sockets 1 & 2 are 'masters' and the wiring is 'straight through' using
> just the two normal 'pins' on the sockets
> 
   A master socket has additional line termination components hidden inside
which are required even when no phone or other equipment is connected. There
are other components to tap off the "ringing" signal. This can be seen by,
and is used by, the BT automatic line testing equipment. There are boxes
which do not contain the termination components that should be used as
secondary boxes. If you are really using two master boxes, the one normally
supplied by BT and an additional one you have fitted, then you could have
problems with your normal telephone system and the REN value, perhaps
causing the line to hold open after calls.
   Another possible problem is ADSL carrier loss both in the interior wiring
and through some cheap but poor quality "microfilters", which can be serious
if you are a long way from the exchange.
   The system used by BT replaces some of the normal line termination
components, leaving just the voltge surge protection components across the
ADSL output, and inserts a very high quality multi-stage filter between the
incoming line and the rest of your phone system. There are about four stages
of balanced filters capable of handling high level signals with minimum
loss, followed by the rest of the normal line termination components. It is
properly designed to allow use with the standard number of phones, faxes,
and modems, (REN = 4), without interacting with the ADSL system. The filter
unit is physically large, and will not fit inside many of the packages sold
as ^ADSL filters^
   If you are on a good line and not too far from the exchange, you may find
that something else will work, but the cost of a BT compatible replacement
front panel can be less than you might pay for a pair of ^ordinary^ filters
and is likely to be more reliable. There are IDC connections for an internal
extension cable behind the replacement front panel as well as the ADSL and
phone sockets on the front.

Street=======Surge protection=======ADSL

                              ||
                              ||
                         Microfilter
                              ||
                       Line termination
                              ||
                              ||=====Phone socket
                              ||
                              ||
                IDC terminals at rear of front panel

-- 
Chris Bell

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