Even then, if I get as far as an engineer visit, I'd have to show him the Hlog and hope he's bothered enough to sort it out.
What would be required in terms of resolving a bridged tap?
This JDSU document explains bridged taps:-
http://www.jdsu.com/ProductLiterature/sctpsbridgedtap_an_tfs_tm_ae.pdf
For anything between your NTE & the cabinet, you would have to rely on an engineer agreeing to check for & remedy any potential bridged taps.
You Hlog graph may assist in convincing him that it is worth checking out.
It is not unknown for bridged taps to have been left in place when D-side cabling partial pair swaps have been conducted over the years, probably from pre-broadband days when a new customer was connected to & the pair extended from a previously ceased connection & when it didn't really matter too much.
In your own home, it could be extension or wiring or even an alarm company having incorrectly connected to the line before or at the NTE.
Maybe a 'dodgy' faceplate or dangly filter could also have a similar effect in that the phone & DSL signals are not sufficiently 'separated'?
I absolutely take your point, BE, but a bridged-tap on the
actual D-side cable is extremely rare. It is more likely to be (as was in your situation), in the Cabinet on the Krone, Quante terminating strips. It
can happen whereby the engineer won't notice there are a pair of wires already terminated on the EU's allocated termination. This is usually due to the amount of wire and position of the strip (generally low down and difficult to see), and they will inadvertently terminate their jumper-wire over the top of the existing wire. I know, as I've done it myself.
There is a
possibility of a bridged-tap on the D-side cabling
if the EU is on an
extremely long line. We used to do 'Bunched pairs' for these rare situations as their landline would be reported as 'Faint'. As touched upon by yourself, it didn't matter with PSTN (Dial tone frequencies).
However, seeing as the OP is getting 70Meg, he must be close to the Cabinet and as such the situation I mentioned above is highly unlikely to pertain to his circuit.