BT Line Problem - strange?

Yesterday my phone stopped working. It's totally dead (no dial tone) and if I ring it I get BT's answerphone service saying "Welcome to BT 1571, the person you are calling is on the phone...".

The DSL router is also having problems but not so absolute. I'm only ~150m from the exchange and using Plusnet's ADSL2+ service. I normally sync at ~2xxxxx kbps and it's rock solid.

I'm now syncing slower, low teens mbps and the noise margin is a lot worse than it was. It seems to fluctuate a bit and sometimes even goes negative. The DSL line does drop frequently.

So what's going on? What takes out the phone but still enables the router to connect albeit with worse performance. Am I right in thinking the phone draws DC power from the phone line but the router doesn't draw any power?

You have a loop (short circuit) on your line, so the exchange thinks you are on the phone - hence the 1571 message.

If you unplug the faceplate from the NTE5, so disconnecting all the internal wiring, is the message still there when you ring the number?
This can determine if the fault is before or after the NTE5.

Having just the phone plugged into the test socket inside the master socket, results in the same thing. So I guess short circuit somewhere on BT's side? Would the DSL router still be expected to work (badly) in this situation?

Yes. It looks like the fault is with the line, so if you haven't already, report it to you telephone supplier.

DSL can still work (usually poorly) with some faults on the line.
It depends upon what the specifics are, but the loop resistance may be low enough for the exchange to recognise it as a loop, but still high enough not to be a complete short and allow a (degraded) DSL signal to pass.

Well, the BT engineer is visiting tomorrow afternoon so with any luck he'll be able to sort it out.

Just the update, the BT engineer came today and fixed it.

I'm in a first floor flat. The cable running from BT's grey box at ground level outside up to my flat has two pair in it, one was used the other spare. The pair I was using had shorted, a loop. But the other pair was okay and he just switched me to that pair.

On the shorted pair the DSL router was reporting a 25dB line loss and noise margin ~0dB. On the new pair the line loss has dropped to 7dB and the margin is now 23dB! It only connected at 15mbps, I guess over time the speed with ramp back up to 20mbps.

However the outstanding question is why the first pair shorted, and if/when the second pair will go down to the same fate.

There was no charge for this visit, but if BT need to pull a new cable there would be a significant charge.

Hi
It only connected at 15mbps, I guess over time the speed with ramp back up to 20mbps.

It depends if you are on IPSTREAM then your profile may have taken a dive because of the problems with your line . In that case it should recover in 3 to 4 days or less. It could also be that The dslam has seen your line as been unstable during the that period so the Target SNR has been raised . In that case it could be along time before you get back to your original synch rate .
Btw with your attenuation you should be able to synch at 24000Kbps.
Might be worth looking at your routerstats.

Regards Jeff

In reply to a post by clv101:

There was no charge for this visit, but if BT need to pull a new cable there would be a significant charge.

No there wouldn't ! BT are very fond of saying this, but they are responsible for all the wiring right up to your master socket, and the maintenance of this is included in your line rental. So you wouldn't pay anything. What the guy should have done is replace the cable, but he took the quick way out. There is a good chance that you'll have problems with the 2nd pair in the future.