My line is 300m (confirmed by Openreach) and my estimates are:

FTTC Range A (Clean) download high 80, low 63.3; upload high 20, low 20
FTTC Range B (Impacted) download high 75.6, low 50.5; upload high 20, low 16.3

There's 120m of aluminium cable in there and now the Cu/Al joints are deteriorating I only get 55 Mbps compared to 74 Mbps about 18 months ago.

My line was checking for speeds at and near max as my NGA is about 250m away but BT Wholesale updated the checker a few times in last few months and each time they have reduced the estimates.

NGA has been in a few years to my knowledge and still quiet a few on Virgin Media round here so not sure why the speeds have dropped..

Most houses have had to have new line installed from the street as most the area was enabled with cable phone lines before BT lines.

Mine is 200m away and getting estimated of 77.8Mb by Openreach. I getting 75Meg in true speed.

In reply to a post by silverfoxxxx:

so maybe I'm not connected to the closest cabinet?

Very possible. My nearest can is literally a stone's throw from my house, but I'm connected to one round the corner of the village green.

It all depends how the houses were build/connected in the first place.

In reply to a post by adslmax:

Mine is 200m away and getting estimated of 77.8Mb by Openreach. I getting 75Meg in true speed.

I wasn't asking what speed I would get, I'm wondering why such a big drop in 3 months and if this is going to get worse "if" more customer from Virgin Media switch over causing crosstalk.

As I mentioned before, most properties in my area do not have a Openreach Line at all to their properties, and nearly everybody had a phone line with cable as they rolled out first.

This is the best of my current understanding about how the checker works...

The estimates made by the BT checker are based on BT classifying your line, and then giving you a range from "similar lines". The top & bottom figures in the range come from the 20th and 80th percentiles of those "similar lines".

What seems to happen is that all lines connected to a DP are given the same initial classification, with an assumption that each line has an average drop wire (or lead-in wire).

For some lines, the back-office database holds the wrong information about the DP. And sometimes the drop wire is a long way from average.

If your estimate changes, it is likely to be because either
a) BT re-classifies your line, so it gets compared with a different set of "similar lines"
- One obvious time this happens is when you order FTTC, and BT gets a chance to check if the original assumptions it made about your line are right.
- A second obvious time is when a neighbour orders FTTC, as BT gets a chance to check some of the original assumptions about the DP.
b) The percentiles of the set of "similar lines" changes.
c) BT's experience changes with added take-up network-wide, and they rebalance the way in which "similar lines" are checked en-mass

OK well, I don't have any "physical" line to my property and why would it change 3x over 3 months and each time it has gone lower and lower.

In reply to a post by mlmclaren:

In reply to a post by adslmax:

Mine is 200m away and getting estimated of 77.8Mb by Openreach. I getting 75Meg in true speed.

I wasn't asking what speed I would get, I'm wondering why such a big drop in 3 months and if this is going to get worse "if" more customer from Virgin Media switch over causing crosstalk.

As I mentioned before, most properties in my area do not have a Openreach Line at all to their properties, and nearly everybody had a phone line with cable as they rolled out first.

My max rate was dropping to 93Meg from 134Meg due to crosstalk but still well above 80Meg thought. My FTTC is now nearly 1 year old.

Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 9.6 15.3
Attenuation (dB) 11.3 0.0
Output Power (dBm) 12.4 -1.4
Attainable Rate (Kbps) 93063 33045
Rate (Kbps) 79987 19999

Edited by adslmax (Sun 04-Jan-15 14:51:52)

You can always upgrade later to a higher speed if estimate proves conservative. Why waste the money going for a package that looks on your figures not to be attainable. I'd just be pleased you can order the fibre work Chard->Axminster has been glacial.

So its likely that Crosstalk has caused speeds to drop and that's caused BT Wholesale to reduce the estimates then.

Has your connection stopped losing bandwidth now or is it still dropping?