Looking at the graphs etc it just looks like crosstalk.
Crosstalk can take huge amounts. People on slower lines often see 30Mbps turn into 15Mbps due to crosstalk.

Crosstalk on my line took 25Mbps. This is why your estimate was around 60Mbps - as that was accounting for the crosstalk. So they expected around 20Mbps of crosstalk at sign up. Clearly this was an overtime thing - so you wouldn't have experienced it immediately. The crosstalk is slightly worse than anticipated which probably just means takeup is higher than expected and you potentially have multiple sources of crosstalk, more than was expected.

Not a lot can be done as far as I'm concerned. SNR is pretty spot on. If interleaving kicks in you'd lose even more which is a possibility.

Edited by ukhardy07 (Sun 14-Jul-13 16:52:07)

Talking about just how much speed that crosstalk can steal from your line...

The Broadband Forum (a supplier group that helps standardise how broadband equipment should work) has a document on vectoring.

Figure 6, on page 12, depicts the effects of crosstalk at various distances (as well as the improvement made by vectoring).

For this discussion, note the difference between the two blue triangles (one upside down) at any one distance. The upper one shows the speed available if it was the only line in the system, while the lower triangle shows the 99% worst case possibility.

At 300 metres, the theoretical best/ideal case is a speed of over 150Mbps, while the worst case is only 50Mbps - so crosstalk causes two-thirds of the speed to be lost.

The blue crosses at each distance show the range of speeds actually seen by a variety of crosstalk-affected lines. At 300 metres, the best line ends up at 95Mbps, while the worst is around 65Mbps. (Note: They probably represent a higher take-up than we have seen in most of the UK so far.)

From what I've seen, BT's estimates, at any particular distance, fall somewhere between the lowest blue cross and the lowest blue triangle.

In reply to a post by RobertoS:

But even if it is a breach of contract, the appropriate course of action for the sufferer is what?

like i said is no immediate resolution.

best case scenario is they get a get out of jail free on their contract.

for ofcom/asa its a numbers game, if this becomes a widespread issue and enough complain, eventually the regulatory hand will be raised.

In reply to a post by WWWombat:

In reply to a post by Chrysalis:

thats ok for new customers but changing the estimate for a line post sale and then using the new estimate to determine acceptable performance is a breach of contract.

Is it really a breach of contract?

I don't see anything in the terms & conditions (I'm looking specifically at BT's Infinity product) that there is *any* level of acceptable performance specified, whether relative to the estimate or not. In fact, there isn't even a statement that relates actual performance to the estimated performance.

I'm surprised, I must say. I thought I'd find something more than I did, but the text only states:

In reference to www.productsandservices.bt.com/consumerOrders/control/termsandcondi...:

The service we agree to give you includes [...] a high-speed fibre broadband service. Your speed will be estimated at the time of placing the order and will be the fastest speed your line can support.

It is hard to argue against this bit: "Your speed [...] will be the fastest speed your line can support."

if ordering over the phone where the speed is quoted it probably is.

on my BT account page my estimated speeds are quoted as actual speeds of product.

One reason why BT and co are allowed to advertise full 80/20 speeds is they are supposed to give out reasonable estimates on order, they become unreasonable when they change post sale. If the speed is already below the estimate on activation and the customer was offered a cancellation, then it might be ok. If the customer initially hit estimated speeds and then the estimated speeds on file get changed post sale and if a fault occurs (loss of speed whatever cause is a fault to end user, they dont care if its crosstalk, or it may be a real fault such as damaged joints) then it can prevent an investigation even occuring as they simply get told they within estimates. I am pretty sure if this happened to me I could could force BT to drop my contract and maybe even refund me. I managed to get them to refund me over DLM as well as cancel my contract obligation.

The hand will raise, and the answer, ensure the sales estimate is well under what a line might be capable of

the hand may also force BT to readjust estimates higher for existing customers to match point of sale.

Note also openreach faults is currently under review by ofcom. I have already sent the report of to them brought up in this thread.

Edited by Chrysalis (Mon 15-Jul-13 19:37:33)

I understand from a technical standpoint why this is occurring. However from a consumer standpoint this is unfair. One should not expect their speeds to drop and pings to rise after the fact by such large margins. I really hope there is some hands raised over this issue forcing BT (wholesale or openreach whatever they are all the same company to me even though on paper they are supposedly not) to change their methodology and for ISP's to be a bit more forthcoming with their info before you signup (Only found out about DLM after I connected).

I really hope vectoring is the so called 'magic bullet' for the crosstalk issue that everyone seems to think it is. Hopefully it is rolled out soon.

In reply to a post by Oddball:

I understand from a technical standpoint why this is occurring. However from a consumer standpoint this is unfair. One should not expect their speeds to drop and pings to rise after the fact by such large margins. I really hope there is some hands raised over this issue forcing BT (wholesale or openreach whatever they are all the same company to me even though on paper they are supposedly not) to change their methodology and for ISP's to be a bit more forthcoming with their info before you signup (Only found out about DLM after I connected).

I really hope vectoring is the so called 'magic bullet' for the crosstalk issue that everyone seems to think it is. Hopefully it is rolled out soon.

Vectoring I feel will be like SRA.

Amazing when it works, but fragile needing right vendor equipment to work right.

The concern I have is that the goalposts have changed (with regards to the estimated speeds) from when I initially signed up with BT Infinity. It does seem easy for BT to get out of this by just saying that there is no fault as I'm within range of their new estimates.

The sync speed is continuing to drop (slowly) over the course of my contract, since I've been with BT Infinity (approx 1 year), but where do you draw the line? Will it continue to drop? When does it actually become an issue?

I know I'm probably stuck, and it's probably not worthwhile pursuing this further, but it is frustrating and even more annoying especially as I was syncing at much higher speeds not too long ago.

In reply to a post by Chrysalis:

Vectoring I feel will be like SRA.

Amazing when it works, but fragile needing right vendor equipment to work right.

I had a look at the latest version of SIN 498 earlier today. I think I told you a while ago that non-Openreach modems have to be vectoring-capable, but I now see something I don't think was there at that time. They are now required to support SRA.