Andrew Benham wrote:
The BT Wholesale Availability Checker
now has a field under "Premise environment" for "Bridge Tap".
The status can be either "U" (for unknown ?), "Y", or "N".
If I check phone numbers where I know there's no DSL, the
status is shown as "U". If I check my number the status is
shown as "N" - good, I have VDSL, and I've made sure there
are no bridge taps. I don't know anyone who has VDSL with
bridge taps, so I can't check for "Y".
But I don't know what status is reported on lines with ADSL
on them. Aren't bridge taps purely a VDSL issue ? So do
lines with ADSL on them have a status of "U" ? Or does the
BT Checker notice bridge taps on ADSL lines as well as VDSL
A friend of mine recently upgraded from ADSL to VDSL and
his status went from "U" to "N". But other numbers I've
tried have statuses of "N" and "Y" - where I think the line
is still only ADSL.
Bridge tap is BT-speak for an unterminated stub on a transmission line.
It will adversely affect any ADSL or VDSL signal. The degree to which
it caused a problem relates to its length, so a long stub will mean
signals are reflected after a longer time delay. It follows that the
higher frequencies used by VDSL will be more likely to be affected by
such a stub.
The website fails at the first hurdle with my number because the ADSL
service is not provided by BT.