[Gllug] [OT] BT phone connections and ADSL

James Roberts jr at stabilys.com
Sat Jun 28 15:20:04 UTC 2008

damion.yates at gmail.com wrote:
> I've just bought a three level flat which doesn't appear to have a
> master BT socket.  The only visible phone connection is a small
> extension socket in the kitchen (the middle level).  My adsl router
> was able to get between 6000 and 8000 kbps which matches what an
> online test showed before I ordered adsl, latency on a basic ping was
> about 12ms, so I wasn't too bothered initially.

> So, what is going on?  How can I find the master socket and will this
> improve matters?

There probably is no master socket. My flat has none. If so, then there 
will be a lozenge-shaped BT master termination near a window or door and 
  an internal-type cable running to the socket. Master sockets were 
introduced post-BT (post '83?), Post Office Telecom did not use them AFAIK.

However this should have no effect on speed.

> Can a cable simply laying next to a phone line cause
> interference that would up latency but not limit line speed?

Yes. You have increased capacitance to ground. But I find it unlikely.

 > Two of the filters I have don't seem to work well

Microfilters? Throw them away and buy new ones. Any thunderstorm zaps 'em.

I refuse to use them - I wire in a master DSL socket but legally, on a 
short link from the incoming BT termination.

 > one causes a
 > landline to ring constantly if plugged in, the other doesn't but both
 > fail to get the line speed over 4Mb/sec, even on their own.

It also sounds to me like the internal wiring is wrong. But first get 
new microfilters.

Certainly it's probable that the extension wiring is wrong.
The old style pre-master wiring depended on a ring capacitor in each phone
(dial phones). The master socket included these.

> I'm tempted to pay BT to come and fit a new master connection, they
> can work out where it all comes from and sort it properly, but I worry
> that I'll not get anyone competant, that it won't fix it at all and
> will be very expensive.

You should not have to pay for a new master socket. However they will 
charge for any extensions.

Good luck.


Gllug mailing list  -  Gllug at gllug.org.uk

More information about the GLLUG mailing list