Plusnet base their decision at least partially on the GEA test result.

The GEA test will fail if a line loses more than 25% of sync speed in a short period of time, I dont know how long that period of time is. Thankfully when my own line went below 50 and I had my pair swap, my GEA test failed for that reason meaning I had some clout to push for a fix.

Edited by Chrysalis (Thu 19-Mar-15 20:59:26)

Thanks for the info all,

My connection hasn't yet lost 25% of its bandwidth though its not to far off, So far I've lost 15.25% and that has been slowly increasing since the issue first began so maybe a week and I will be allowed a visit!

So I've got to wait for it to hit 44.25 Mbps before I can get an Openreach engineer!

Well I had a message today saying below 50Mbps and I've done a few tests today that have come in at less than that so I think thats my VIP pass to meet an Openreach employee...

Should I feel lucky or excited!

In reply to a post by mlmclaren:

No offence but in English please?

OK.

But start by understanding that BT expect your speed to drop as a natural event, as other subscribers get added. You should expect it to happen too.

BT shows you the amount they expect the speed to drop by giving you the estimated speed in a range.

In reply to a post by WWWombat:

The Openreach ranges are the 20th percentile and 80th percentile, so there are people on similar lines outside the range.

"Percentile" is a statistical concept, used as follows:

In order to come up with your estimate, BT compares your line to a whole host of "similar lines". It then considers the full variation of speeds on those lines, and extracts two values...

The first value, used as the upper end of your estimate range, represents the "80th percentile"; this is the speed where 80% of the "similar lines" have lower speeds, and 20% of them have higher speeds. If your line achieved this speed, it would be in the top 20%.

The second value, used as the lower end of your estimate range, represents the "20th percentile"; this is the speed where 20% of "similar lines" have lower speeds, while 80% have higher speeds. if your line only achieved this speed, it would be in the bottom 20%.

When you look at the estimated range that BT provides you with, you can see that 20% of those "similar lines" get a speed below the bottom of the range, 20% get a speed above the top of the range, and 60% of lines get a speed inbetween.

Openreach won't generally accept a fault from the ISP, for just speed issues, until you are below the 10th percentile.

When Plusnet raise a fault with BT for a line fault or a speed issue, BT make a choice about whether to reject that report without sending an engineer.

When the fault report is just for a speed issue without an underlying copper issue, Openreach have been getting more stringent about the faults they accept. One of the specification of FTTC between BTW and ISPs (hidden away out of public sight) is that they will only accept faults that are *just* about speed if the speed has gone below the 10th percentile, or has dropped by a significant amount in a short space of time (IIRC, a drop of more than 25% in less than a week, but I might be wrong).

In that specification, the "10th percentile" represents the speed that the slowest 10% of "similar lines" gets; this speed will be quite a level below the bottom of the estimate range that you have been quoted (ie the 20th percentile).

So when will openreech intervene with an issue?

Openreach will consider any fault sent to them by Plusnet, but will reject it if it doesn't meet the requirements I mentioned earlier. Plusnet know this, so don't bother wasting their time in raising the fault in the first place.

Note:
If you have some evidence that there is more to the fault than just a drop in speed, then Plusnet should take that into account. When you contact Plusnet about a drop in speed, they will also use some of the automated line test tools to check out the physical line for signs of a fault. In either case, if there is evidence of some sort of line fault behind the speed drop, they will raise the issue with Openreach, who are likely to involve an engineer.

However, if there is no sign of a physical fault, and *only* a reasonable drop in speed, they will not involve an engineer.

Why?

Because they expect the VDSL2 lines to drop in speed. They expect speed drops to happen slowly over time, as take-up increases. And, separately, they know that DLM intervention can cause a speed drop too.

As these are known events that are expected to happen - and because an engineer cannot fix anything in the former case, and because the main cause of the latter case is in-home wiring - they aren't willing to send an engineer out.

How much percentage of a speed must one lose before they will get of their thrones!

More than 25% in a 3 or 4 day period will do it.

Or when your speed has dropped well below the bottom of the *current* estimate range. In this case, your ISP has told you the level it will have to drop below.

In reply to a post by WWWombat:

In reply to a post by mlmclaren:

How much percentage of a speed must one lose before they will get of their thrones!

More than 25% in a 3 or 4 day period will do it.

Or when your speed has dropped well below the bottom of the *current* estimate range. In this case, your ISP has told you the level it will have to drop below.

Plusnet didn't give me a range for my line, only an estimate (56Mbps),

also my line was not physically existent until ducting was installed in the ground and an Openreach engineer spent a few hour putting new cabling in a connecting a "new" pair in every junction from the front of my house to the PCP.

You should be able to get the range from http://www.dslchecker.bt.com/adsl/adslchecker.welcome
I'm not sure how they use the clean/impacted figures to decide a threshold for getting out an engineer.

Hi thanks I had thought of that but I'm thinking of the approach to Plusnet as they sold me something and failed to mention that within a month I would lose nearly 15% of bandwidth and go from having the best latency and great online gaming experience to not being able to play online gaming anymore.

Also I've noticed that my speedtest.net server seems to think I'm up by Sheffield usually it put me locally by Maidenhead and ideas why this has happened.

This is what BT Wholesale is reporting for my line (Phone Number)

http://tinypic.com/r/2087k3n/8

So my connection is right at the low end of an impacted line which is amazing considering how new the local network is and the also the absolute silence on my phone line..

Surely getting 50mbps on this line should mean an Openreach visit, the FTTC service around here is not exactly that busy nor is it new..

Enabled in 2011 and when I was the 67th line to be connected (not active I must add) and most this area is still using Virgin Media as nobody fancy's their drives being dug up to install the ducts to their homes.

In reply to a post by StephenTodd:

I'm not sure how they use the clean/impacted figures to decide a threshold for getting out an engineer.

I'm not entirely sure when they use one band or the other.

"clean" means that you have the line working in the proper, expected way for that line. No internal wiring issues, no external wiring faults.

"impacted" means that the presence of faults cannot be ruled out - usually because a self-install was done.

If you had an engineer install, then he should have been able to do enough tests to have your line working within the "clean" range. The engineer ought to be savvy enough to make sure there is no impact from internal wiring, and there are no faults on the external side.

If you had a self-install, then your line could fall into the impacted side, simply because no-one skilled has been confirmed to have checked the line out - even if you have personally made sure there are no internal issues.

BUT...

If the line was a self-install, does this mean Openreach won't send an engineer until your speed drops off the bottom of the "impacted" range, rather than the clean range?

I'm not so sure. The "impacted" range implies there are line faults - which ought to be detectable by other tests; Openreach ought to still send an engineer when you see speed drops alongside line faults.

However, they may want you to take steps to ensure that the problem is not caused by an issue with the internal wiring. Usually they do this by making you take the faceplate off to disconnect the extensions.

In reply to a post by mlmclaren:

So my connection is right at the low end of an impacted line which is amazing considering how new the local network is and the also the absolute silence on my phone line..

Absolute silence below 4 kHz ! With a low pass filter in there to keep the noise out too ... not really surprising.

If your hearing was capable of working up in the tens and hundreds of kilo-hertz you would certainly not be hearing silence. The cross talk from other ADSL and VDSL lines would be very noticeable.

In reply to a post by mlmclaren:

So my connection is right at the low end of an impacted line which is amazing considering how new the local network is and the also the absolute silence on my phone line..

I thought you said your line was syncing at 56,000?

That is still above the bottom of the clean range - so is certainly above the cutoff that Openreach will consider.

That's just below the range you show in the link, but what is the current estimate looking like?

Even just below the original clean range means you are just below the 20th percentile, but you likely aren't yet down to the 10th percentile - which is the threshold at which Openreach take action.

Surely getting 50mbps on this line should mean an Openreach visit, the FTTC service around here is not exactly that busy nor is it new..

Wasn't your mention of "50-52" a reference to download speeds on a speed test?

Your download speeds are of no concern to Openreach; they care about the line speed (ie sync speed). Note the output of the DSL checker: for FTTC, it only quotes line rates

With a sync speed of 56Mbps, you'd expect a download speed to be a maximum of 54Mbps, no higher; there is at least 3.3% in overhead in the various addressing protocols, which doesn't get measured by a download speed tester.

Getting download speeds just below the absolute maximum is the norm; there are many other places that can incur delays in the data stream. I personally find that Plusnet's speeds are a tad below the absolute maximum too - presumably as a result of the way they setup their management system, and having their own QoS system.

Enabled in 2011 and when I was the 67th line to be connected (not active I must add)

Connected in what way, if not active? Connected to what? The DSLAM?

Anyway, 10 lines can be enough to have most of the effect of crosstalk. Even 1 line can be enough, if it just happens to be the one major disturber.

and most this area is still using Virgin Media as nobody fancy's their drives being dug up to install the ducts to their homes.

So the developer didn't put any Openreach ducting or chambers in, leaving an effective lock-in with VM?

I presume they got a good kickback from doing that - as such, would be a developer I wouldn't touch with a bargepole. It sounds good to some people, but only ever turns out to restrict freedom of choice down the line.

Edited by deleted (Fri 20-Mar-15 11:10:04)