On 30/12/2012 12:04, Dave Liquorice wrote:
On Sun, 30 Dec 2012 11:12:47 +0000, David Hill wrote:

I posted about the problem I had with my phone over Xmas, internet OK
but the phone was dead.

A "phone line" uses a single pair of wires from your property to the
exchange.

For the phone to work there needs to be a DC path up one wire and down
the other, this is for on/off hook signalling, pulse dialling and power
to the phone.

The ADSL signal is an RF signal using lots of individual carriers space
about every 4kHz from about 30kHz up to 1.1MHz (up to 8Mbps servive) or
2.2MHz for the up to 20Mbps service.

If there is a small break in one or even both wires the lack of DC path
stops the phone working but the RF ADSL signal can jump across the break
and continue working, though it may well be degraded.

Well BT found a line fault away from the property and fixed it without
a home visit,

Presumably you told faults that the broadband was still working and the
phone not. If this information was passed to the engineer all they would
have to do would be to find you pair in the exchange, attach their
time-domain reflectometer (TDR) and measure how far away the break in the
cable is. He'll know the physical cable routes and location of junction
boxes and given the distance will know which one to visit to fix the
fault. Presumably they rang you up to check the line was back working...

http://en.wikipedia.org/wiki/Time-domain_reflectometer

Why "Not" OT?

Three years ago I lost broadband, although still had the phone working
ok. Openreach came round and before they examined anything said it was
an inside problem - almost certainly the modem or internal extension
lead. Keeping my cool, I asked them how, if it was the modem, how come
the same fault applied to the two different types and makes of
modem/router I had? And if it was the extension lead, how come the
fault was still there if I used the internal socket of the NTL5 (I used
"NTL5" rather than "Master" socket). They kept quiet after that and
replaced the NTL5, eventually getting the broadband signal back after
quite a bit of fiddling with the wires.

Less than a week later I lost the phone (but the broadband still worked.
They came round again after running tests at the exchange and this
time concluded it was a line fault. Calls were diverted to my mobile
for 10 days before they sent someone to dig up 10 metres of pavement and
a trench in my front garden to replace and reroute the cable.

In doing so, he had to cut through the roots of a couple of large
shrubs, one being a ceanothus which, when it snowed a couple of weeks
later, fell over due to the weight of snow on it and having a
"one-sided" root system! That's why it's not "OT"!

--

Jeff