Availability checker wrong who maintains?

Hi the BT availability checker states:

You can choose BT Broadband now offering:

12Mb *
Estimate download speed

7Mb-17Mb Download speed range

However my line is about 3.5-4km from the exchange and I get 3.5MB ish

My ISP (Bethere) uses the same data as when I called to enquire they said your line can get those speeds!! - I explained I have a new router and microfilter connected to the test socket - no extensions interfere (as I use DECT phones)

the Guy said he'd tweak my profile and upon trying to get better speeds realised the database is wrong!
He did a check to confirm the line distance etc

Is there a method/process to get this fixed as its annoying to see stuff offered I know I cant get..

Thanks

The BTw Availability Checker has no idea of BB performance with LLU providers and does not accept input from them. Its database is based only on historic line lengths updated by speeds whilst on BTw products.

What is the attenuation, downstream and upstream for the line?

The ISP you pay should be able to feed this back up the chain, eventually ending up with Openreach

In reply to a post by MrSaffron:

What is the attenuation, downstream and upstream for the line?

The ISP you pay should be able to feed this back up the chain, eventually ending up with Openreach

Line Attenuation (Up/Down) [dB]: 18,8 / 56,5

BE there support stated they have no mechanism to inform BT the data is wrong!

I realise it makes no odds to anything but I'd like the data to be right so that as tech marches forward I can move to a faster sollution once it exists!

18,8 / 56,5

There is an imbalance with those figures, would expect a downstream attenuation more like 36dB. 56db downstream attenuation will be around the 4 to 5 Meg maximum.

This suggests that if some measurement systems are made it might reasonably think 12 Mbps is possible.

Does not happen to be some aluminium in the line?

Edited by MrSaffron (Fri 19-Apr-13 17:41:20)

In reply to a post by XRaySpeX:

The BTw Availability Checker has no idea of BB performance with LLU providers and does not accept input from them. Its database is based only on historic line lengths updated by speeds whilst on BTw products.

Well my line length hasnt changed the checker used to say 2.5-3MBs now its far higher at 10-17!!

In reply to a post by MrSaffron:

18,8 / 56,5

There is an imbalance with those figures, would expect a downstream attenuation more like 36dB. 56db downstream attenuation will be around the 4 to 5 Meg maximum.

what would cause an imbalance - an old/noisy line?

I get about 3.5MBs

Bad copper or possibly aluminium.

Basically looks like low frequencies are OK, but something is attenuating higher frequencies.

How sure on you on the physical line length. As a rough conversion is that every 10 to 12dB of downstream attenuation is a KM of cable

I didnt think ADSL ran over aluminium?

Anyway just under 4km apparently

which translates to about 48db based on your rule of thumb.

Do you think my ISP will raise a ticket (I'm doubtful given the line length)

Aluminium works, just gives more attenuation per km, and degrades quicker than copper. Copper cables if not attacked by trees can last decades, hence choice of copper originally.

Unlikely, solution is to just ensure you know to take any speed estimates with a pinch of salt and rather base them on what you know your line is capable of.