Ceasing VDSL and providing ADSL instead - what's involved by BT?

Discussion in 'Broadband' started by NY, Jun 30, 2014.

  1. NY

    NY Guest

    A client of mine has just moved into a house where the previous owner had
    VDSL (they were told he had "fibre broadband"). The new owner took out a
    contract for ADSL broadband and was given an activation date of last week.

    But when I went to investigate, there was no ADSL carrier detectable at the
    RJ11 socket on the faceplate of the master socket: I used my Netgear router
    which shows attenuation, noise margin and sync speed (which it's difficult
    to get a BT hub to do) and there's nothing.

    BT believe that everything is OK, from all the line tests that they have
    run.

    I wondered: what could go wrong? When BT cease VDSL and provide ADSL, is it
    purely a software configuration change at the exchange or does it involve
    moving their phone line pair from one rack of VDSL equipment to another rack
    of ADSL equipment?
     
    NY, Jun 30, 2014
    #1
    1. Advertisements

  2. That would be "fibre to the cabinet", FTTC. There is a fibre
    connection from the exchange to the cabinet (usually within a few
    hundred metres of your house) and a VDSL connection from there to your
    house.
    With FTTC you are connected to a VDSL DSLAM modem in the cabinet.
    With orindary ADSL you are connected to an ADSL DSLAM in the exchange.
    Switching back from FTTC to ADSL will require rewiring your connection
    in the cabinet.

    -- Richard
     
    Richard Tobin, Jun 30, 2014
    #2
    1. Advertisements

  3. Its worse than either. Its a rewire of the voice line at the voice exchange.


    --
    Ineptocracy

    (in-ep-toc’-ra-cy) – a system of government where the least capable to
    lead are elected by the least capable of producing, and where the
    members of society least likely to sustain themselves or succeed, are
    rewarded with goods and services paid for by the confiscated wealth of a
    diminishing number of producers.
     
    The Natural Philosopher, Jun 30, 2014
    #3
  4. Really? I thought that with FTTC the voice connection went from the
    exchange to the original cabinet as normal, and from there to the
    VDSL cabinet.

    -- Richard
     
    Richard Tobin, Jun 30, 2014
    #4
  5. NY

    NY Guest

    And given the lack of broadband carrier, I'm wondering if that work was
    carried out - although you'd think remote diagnostic tests (and looking at
    the worksheets for the Openreach engineers) would establish that.

    I could be completely wrong in my diagnosis - lack of detectable broadband
    at the master socket could have many causes - but the fact that the previous
    owner had what sounds like FTTC and VDSL from the cabinet rang a few alarm
    bells and I thought "I bet that complicates things a bit" ;-)
     
    NY, Jun 30, 2014
    #5
  6. NY

    Bob Eager Guest

    And rewiring in the exchange - to provide the ADSL.

    And probably a new 'master socket' in the premises.
     
    Bob Eager, Jun 30, 2014
    #6
  7. NY

    Andy Burns Guest

    Sorry I was reading that backwards, i.e. starting at the premises-end
    rather than the exchange end.
     
    Andy Burns, Jun 30, 2014
    #7
  8. NY

    Kraftee Guest

    Not necessarily as many VDSL users remain connected to the DSLAM in the
    exchange as well as the PCP. Don't know why, nobody I've asked appear to be
    interested so I just observe and keep quiet.
    Nope as the same filtering system used for VDSL is suitable for XDSL

    Sounds like BT have just switched the service over/on and because it appears
    to test ok then the engineering visit has been cancelled.
     
    Kraftee, Jun 30, 2014
    #8
  9. NY

    Andy Burns Guest

    Presumably, though connected, the ADSL DSLAM would be shut-down on that
    line, leaving it up to the VDSL DSLAM?
     
    Andy Burns, Jun 30, 2014
    #9
  10. Not necessarily as many VDSL users remain connected to the DSLAM in
    I agree, my downtime for the ADSL to VDSL upgrade was a few seconds, as the
    PCP cabinet jumper was swapped, ADSL disappeared, and VDSL appeared as I
    swapped the router lead from ADSL to VDSL modem.

    I assume the VDSL DSLAM has filters that removes exchange ADSL from the
    line before adding VDSL. Can not believe that BT co-ordinates engineers at
    cabinet and exchange to remove ADSL at the same moment as switching in VDSL.
    If they run out of ADSL ports in the exchange, maybe they'd recover ports
    migrated to VDSL, but seems unlikely to be necessary.

    Angus
     
    Angus Robertson - Magenta Systems Ltd, Jun 30, 2014
    #10
  11. NY

    Graham. Guest


    It is definitely true that with ADSL, the customers modem (CPE) has to
    be on line before the DSLAM will respond with a signal. so a line with
    no modem is, for all intents and purposes, a non ADSL line.

    I can't say if that is equally true of VDSL

    Neither can I say if an ADSL modem will detect the presence of a VDSL
    signal by changing the colour or cadence of its ADSL carrier LED,
    which the OP was assuming was possible.
     
    Graham., Jun 30, 2014
    #11
  12. NY

    NY Guest

    As the OP, I'm not sure that I was assuming this.

    I noticed the expected change of colour of LEDs (IIRC, it should go green,
    blue, orange, blue) as far as the third step when the ornage LED was
    accompanied by a red flashing "b" which indicates a non-specific broadband
    fault which in this case, by use of a Netgear router, corresponded to "no
    ADSL carrier - no noise margin or attenuate figures given, 0 upstream and
    downstream sync speed". In other words, the same as you'd get if the router
    was unplugged from the phone line.

    One curiosity in the documentation for the BT hub was the statement that
    even after the line has been activated, it may take 24 hours of connection
    to the line before the flashing b disappears and you get broadband. I've
    never seen any other router say anything to that effect. If broadband is
    present (by which I include "free of unfiltered phones and other customer
    wiring problems") then the router will at least register the presence of the
    carrier immediately, even if it takes a while for the router to log on with
    the customer's ADSL username/password. Sync speed may be lower than normal
    until the DSLAM and router negotiate the best rate possible over that line,
    but it should always connect.
     
    NY, Jun 30, 2014
    #12
  13. Are you sure it's not just that the VDSL equipment in the cabinet is
    also ADSL2+ compatible and will talk to an ADSL2+ modem if the customer
    puts one on the line?

    That seems FAR mode likely to me that the idea that it's still possible
    to get an ADSL/2/2+ signal all the way back to the exchange.
     
    Brian Gregory, Jun 30, 2014
    #13
  14. Openreach just fixed a problem on my ADSL line. As part of this they
    fitted a VDSL faceplate, so presumably they are using this as standard
    for everything now.
     
    Mike Tomlinson, Jul 1, 2014
    #14
  15. NY

    Andy Furniss Guest

    Technically maybe, but that would mean openreach giving a free upgrade
    (shorter line = better speed) to the service and using up a vdsl port
    that they may need and have quite different pricing policies for.
     
    Andy Furniss, Jul 1, 2014
    #15
  16. NY

    Brian Mc Guest

    : With FTTC you are connected to a VDSL DSLAM modem in the cabinet.
    : With orindary ADSL you are connected to an ADSL DSLAM in the exchange.
    : Switching back from FTTC to ADSL will require rewiring your connection
    : in the cabinet.

    I am not sure this is correct!

    The FTTC cabinet is nearby to the POTS one (the "cab") - but the copper path
    to the exchange is untouched - as it is still used for voice calls. There
    is a crossover cable connecting the cab junction (in parallel) to a modem
    in the FTTC cabinet.

    As the copper path to the exchange remains as it always was reverting to
    ADSL surely just means disabling the FTTC modem and reconnecting the DSLAM
    at the exchange end. The crossover cable could even be left to be reused
    for the next FTTC customer.
     
    Brian Mc, Jul 1, 2014
    #16
  17. NY

    Andy Burns Guest

    It is touched, with ADSL the copper path goes

    house->oldcab->exchange

    with VDSL the copper path goes

    house->oldcab->newcab->oldcab->exhange
     
    Andy Burns, Jul 1, 2014
    #17
  18. NY

    NY Guest

    My client has finally got BT Internet to agree to send an Openreach engineer
    so hopefully I'll hear back what he found.
     
    NY, Jul 1, 2014
    #18
  19. NY

    Brian Mc Guest

    : Brian Mc wrote:

    : It is touched, with ADSL the copper path goes
    : house->oldcab->exchange

    : with VDSL the copper path goes
    : house->oldcab->newcab->oldcab->exhange

    I stand corrected! I thought that the connection to the "newcab" was just
    "t-ed" off the existing connection in "oldcab"
     
    Brian Mc, Jul 1, 2014
    #19
  20. NY

    Kraftee Guest

    You forget, the line has to pass thru the VDSL DSLAM in order for the
    infinity service to work, effectively isolating the exchange DSLAM. To be
    reverted/connected to ADSL then the jumpering in the PCP has to be change to
    disconnect the VDSL DSLAM
     
    Kraftee, Jul 1, 2014
    #20
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.