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[Oldjim]

As part of my investigation into a bit swapping problem I read this very useful page - congratulations.
However looking at the graph here http://www.kitz.co.uk/adsl/adsl_technology.htm#long_line it is exactly what I was seeing when on 20CN but when I moved to 21CN (still on ADSL1) it changed quite dramatically and all my previous intermittent loss of sync problems vanished. These sync problems always happened when the phone rang but not every time the phone rang if that makes sense.
This is with a 51dB attenuation line
Before is on the right and after on the left.
The reason for posting this is that in my case it would appear that the reduced loading on the lower frequency tones was due to an exchange problem and I wonder if your example was showing the same type of problem

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[kitz]

>> The reason for posting this is that in my case it would appear that the reduced loading on the lower frequency tones was due to an exchange problem

Although I cant be certain..  and I could be wrong..   my guess would be that it was likely to have been some sort of  NeXT on the old 20CN dslam, which is not present on the 21CN MSAN.

Ironically on a very short line (adsl2+ msan),  I seem to suffer far worse with Cross Talk at the MSAN, which is affecting midrange tones.  


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edit

Should clarify.. that although you are still on adsl1...  the MSAN itself will obviously adsl2+ enabled and will now have users on it who are using the full adsl2+ spectrum.

[Oldjim]

That is an interesting suggestion and, if correct, I wonder why the numerous BT fault investigations failed to find it.

[kitz]

Possibly because atm nothing much can be done about near end crosstalk, (unless its an actual fault on the line-card)  and there will always be a certain amount of crosstalk at the DSLAM/MSAN.
The amount of xTalk can vary from msan to msan depending on the lines bundled to it.