I'm pretty sure that BT have records of the attenuation value for linesWhat about lines that never had BB on them? Or even ones that never had BTw BB? Wouldn't imagine BT had attenuations for those.
My comment is based on section 2 of this Sagentia report for Ofcom
. It states:
The main data required for this study was the statistical distribution of line lengths and
types for the millions of copper loops in the UK. We have obtained this data from
public domain sources.
A paper for NICC DSLTG by John Cook presents the cumulative distributions for BTís
network of line length for exchange to customer and cabinet to customer in the form of
We know of attenuation being determined by DSL modems, and being tested by the diagnostic woosh tests. However, they aren't the only way in which attenuation can be figured - there are indeed single-ended line tests that can be performed at the exchange that give this result.
So it is certainly possible for BT to measure the attenuation of every line in the country, whether it has DSL or not. And we know that BT perform routine line tests every 24 hours too.
But whether they *have* performed tests for attenuation on all their lines is unknown.