BT Retire 20CN IPStream Connect Broadband Services at 425 UK Exchanges

BT has informed UK ISPs that its legacy broadband retirement programme will, from November 2012, stop accepting new provide orders for its older 20CN based IPStream Connect products (e.g. mostly up to 8Mbps ADSL technology); albeit only at telephone exchanges where the latest 21CN based Wholesale Broadband Connect (WBC) solution exists as an alternative.

Many of BT’s remaining 20CN based services exist in predominantly rural areas, which are usually classified as Market 1 by Ofcom (covers around 11.7% of UK homes and businesses or 3 million premises). But many of these exchanges will soon benefit from the operators plan to make the latest 21CN / WBC services available to 90% of the UK (22.5 million premises) by the end of Spring 2013.

Martin Pitt, MD of UK ISP Aquiss, said:

“This rolling programme will cover 2,500 exchanges at the rate of around 400 a month until IPStream Connect is fully retired across the WBC estate by 31st March 2014. IPStream services will remain available at those exchanges not enabled for WBC copper broadband.

We are providing early notice to customers now and will also advise how and where existing connections need to be moved from IPStream Connect to WBC based services.”

Most consumers should not expect any major disruption from this change because the ISP will normally take charge of moving customers from one platform to the other. Indeed many could benefit from the faster speeds offered by ADSL2+ and other solutions on 21CN, although experiences do vary.

1. Phil

   May 11, 2012 at 12:47 am

   bad news for those who still stuck on 2Meg!
2. Deduction

   May 11, 2012 at 1:23 am

   Or anyone a long distance from exchange as ADSL2+ performs worse than ADSL at distance.
3. Martin

   May 11, 2012 at 2:11 am

   As Market 1 victim I expect to be on 20CN until 22CN…
4. Andrew Ferguson

   May 11, 2012 at 9:07 am

   @deduction, if a modem performs worse on ADSL2+ then solution is to switch to ADSL mode. Providers have this option to do so remotely.

   ADSL2+ is more sensitive to noise, so poor wiring can be an issue if not dealt with, that and old modems whose ADSL2+ microcode is not up to date.
5. Phil

   May 11, 2012 at 12:36 pm

   I think all isp’s should provide high end performance router, not a cheap or rubbish router. I been helped my neighbour who suffered loss of wi-fi and poor speed of 4 meg with BT and I lend her a high end performance router for a month trial, she had no wi-fi loss issues at all, speed was solid and faster at 12 meg. It because BT gave her cheaper and rubbish router.
6. Michael

   May 11, 2012 at 1:17 pm

   Interesting blend of observations.

   If I remember rightly the ADSL2+ Spec provided better noise immunity than ADSL, but of course it does depend on the quality of engineering in the router – and how well it “matches” the Exchange DSLAM line card capabilities.

   In this country due to the regulatory regime it is not possible for BT Wholesale to declare which manufacturers ADSL/ADSL2+ CPE perform best – even though their DSLAM statistics, and Lab tests did tell them.

   As a result, as customers we have the choice of 20 to 30 different routers – all ADSL/ADSL2+ compliant but totally different qualities. In countries where the carrier matches DSL router to DSLAM line card optimisation they can predict speeds better and also their national average line speeds are higher in real terms.

   We are beginning to see this effect in the UK FTTC market where VDSL2 modem matches FTTC VDSL2 DSLAM.
7. SpencerUk

   May 11, 2012 at 2:45 pm

   BT has been getting slowly shut from around 18 months ago..Nothing new really here :/

   Considering 20CN costs more to provide on than 21CN it makes sense for ISPS to put you on 21CN 🙂

   @Andrew Ferguson …ADSL2 is not necessarily more sensitive to noise at all, its the fact that DLM tries to predict EVERYTHING before it actually happens…Credit to Wholesale though, they have tweaked things and its loads better than what it was 18 months ago…
8. Deduction

   May 11, 2012 at 4:15 pm

   ADSL2+ even with an ADSL profile set on 21CN can give issues. For a start as indicated above the DLM system can become confused. Very long lines can have even further issues, not only with downstream but issues supporting the higher upstream rates of ADSL2+ (which AFAIK can NOT be altered remotely, if you alter a profile to ADSL it will still AFAIK try to connect at the new higher upstream, unless BT have some new system in place to bypass that).

   The biggest problem with ADSL2+ on long lines isnt normally noise but poor attenuation. Leading to any system that uses DLM setting high Noise Margin and resulting in dog slow speeds.

   This also in no way actually helps those with long or poor quality lines to achieve the so called promise of 2Mb for all which BT and the government have been harping on about for god knows how long.

   Understandable why BT have done it, the right thing to do though or a good thing… Absolutely not!
9. Tom

   May 11, 2012 at 4:47 pm

   “supporting the higher upstream rates of ADSL2+ (which AFAIK can NOT be altered remotely”

   I have at least one customer on 21cn but limited to 8mbps down and 448kbps upload at ADSL1 only.
10. Phil

    May 11, 2012 at 9:43 pm

    WBC ADSL2+ offers upstream options of 448, uncapped and where applicable, Annex M.

    Once on these, upstream target margins can also be applied at 6 & 9dB. Annex M has additional banded profiles like those available on downstream in place of target margins.

    These upstream target margins can be applied via the SNR reset functionality provided to ISPs and will kick in any time upto 4 hours from it being initiated, though DLM still applies.

    Fixed targets can be applied to, through means of effectively turning DLM off. This is achieved by making the line think it has a indicating line quality of Amber at all times (red means DLM causes higher target margin or banding, green means the line is not defecting so could support a lower target margin, adjusting appropriately).
11. Deduction

    May 11, 2012 at 10:07 pm

    IF that is the case then i stand corrected on the part regarding upstream 🙂

    The only other issue i can think of if you are a BT retail customer is explaining to the over seas support you want/need all that tinkering done. I can not imagine the DLM system has got to the stage where it is smart enough to do all of what Phil describes by itself when its needed. (though maybe im wrong on that also, in which case that would be impressive).
12. Phil

    May 12, 2012 at 12:15 am

    Haha, it does it far from by itself. BT will only support it (in the area of low sync, high errors and dropping connect) in default stability (standard DLM). Then there is stable (aggressive DLM, requires fewer errors to bump the target or utilise banding).

    Then there is custom. You essentially tell DLM at which point it should consider the average time between errors is too small (an average of 300 seconds is worse than averaging 3000 seconds), as to with the mean time between retrains.

    To be fair, DLM is most certainly smart enough. After all, it is simply a set of rules based on collected information. Mainly MTBE (Mean Time Between Errors) and MTBR (Retain equivalent).

    Few providers use it because DLM despite hatred, has its place. It’s designed to replace human need to raise a fault to cure simple minor quality issues. It also has the reverse impact on a line when you play with it. Whilst you may get a faster speed and no longer see a 10 min burst of noise from your neighbours old B&W telly cause you to lose 2Mbps for weeks, prolonged noise may mean you line is never stable until the noise is gone. DLM is a coping mechanism, albeit a flawed one.

    The custom stuff was never intended to disable (I should rather term it, move the goal posts so it can never play with your SNR) DLM, but allows provided to define their own thresholds for what is an acceptable volume of errors/retrains.

    As has been said, DLM on its own has improved in the last 18 months. This was done simply by changing the acceptable number of errors before tipping a target change.

    Providers now have the choice to do their own target change, if they feel BT should do a further one.
13. DTMark

    May 15, 2012 at 12:39 pm

    Twentieth century network 😉

    My estimate for this area, given the shortest line is just over 2500m long and the average downstream is 2.7Mbps, was that about 15 properties would potentially benefit from an increase in downstream speeds if the exchange were upgraded to ADSL2+

    Given nearly all lines have noise ratios of 12 and above and half have poor performance for their length I suspect this is one of the reasons why the exchange has been marked for upgrade before but then quietly dropped, the other being that 3G is the only competition – that said even 3G beats ADSL here on the downstream and massively so on the upstream and on our line would continue to do so even it were ADSL2+.

    I thought I remembered reading that some countries such as NL didn’t even bother much with ADSL2+ as it was viewed as a waste of money to put money into copper based solutions, as this country’s average broadband speed clearly demonstrates.
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