BT_ADSL_CODE FAQ V1.0

Can I get ADSL on my line?

The various ISP and BT line checkers all access databases which return
a 4 letter code for the phone number entered. This code is usually
referred to as the BT_ADSL_CODE and has 4 letters, for example AGRB

You can find the code by looking at the URL or the source code (text
search for "BT_") of the results when you input a number into a
checker, for example at www.bt.com/broadband its at the bottom of the
source code of the pop-up results box, with BT Yahoo its early in the
URL of the results page. BT try to conceal this code so you may have
to hunt around for a working number checker that discloses it.

The first two letters are codes Red Amber Green for the different ADSL
services. Green means the line is believed to be OK and an order will
proceed automatically, Amber means the line is borderline and further
work will be done to regrade it to G or R. Red means the line is too
long (loss too high) and an automatic order will be rejected. ISPs can
place a "manual order" for further testing if the Red code seems
wrong, for example if your neighbours have ADSL but your line shows up
Red.

The 1st letter refers to the 1 and 2 Mbit/s ADSL services, these are
good for line losses up to 45 dB (~3.5 km line length)

The 2nd letter refers to 512kbit/s RADSL services which work up to 60
dB loss (6 km) and may reduce the upload speed from 256kbit/s down as
far as 64 kbit/s in order to cope with line quality. In practice this
"rate adaption" is rare.

The 3rd letter indicates the exchange status:

E enabled, ADSL is available
N not available
R taking registrations
P planned, trigger reached and activation planned

The 4th letter refers to services on the line:

A means the line has ADSL
B or I are Home/Business Highway and ISDN lines
E is a DACS line sharing device
P means there are other incompatible services
R means an order is placed for ADSL on this line
Z means there are no incompatible products or service on the line

Sometimes you will see an odd code like AAEZ, this usually occurs if
you are fed with TPON fibre and would need changing over to a copper
line to get ADSL. As the copper isn't defined the database doesn't
know how long the line is so puts Amber on both services.

Tiscali, Plusnet and others offerring 150k or 256k speeds are doing so
by using the standard BT 512k product and throttling it either at the
exchange or elsewhere, so there is no distance advantage in these
products, only a lower price.

Phil
V1.0 13/12/03

"Phil Thompson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Can I get ADSL on my line?

Useful but a couple of comments if I may.

> The first two letters are codes Red Amber Green for the different ADSL
> services. Green means the line is believed to be OK and an order will
> proceed automatically, Amber means the line is borderline and further
> work will be done to regrade it to G or R. Red means the line is too
> long (loss too high) and an automatic order will be rejected. ISPs can
> place a "manual order" for further testing if the Red code seems
> wrong, for example if your neighbours have ADSL but your line shows up
> Red.

It may be worth stating that if a test hasn't previously been carried out on
a line the automatic checker is a "best guess" based on ppaer records etc..

> The 1st letter refers to the 1 and 2 Mbit/s ADSL services, these are
> good for line losses up to 45 dB (~3.5 km line length)

41dB with no ADSL equipment fitted
45dB with ADSL equipment

> The 2nd letter refers to 512kbit/s RADSL services which work up to 60
> dB loss (6 km) and may reduce the upload speed from 256kbit/s down as
> far as 64 kbit/s in order to cope with line quality. In practice this
> "rate adaption" is rare.

60dB with no ADSL equipment fitted
64dB with ADSL equipment

> The 4th letter refers to services on the line:

When this FAQ comes to the attention of BT - they will object to listing
what the 4th letter means. Even though tis is known to may people, it
apprtantly leads to Data Protection issues (I think) re: revealing what
services are on other customers lines.

As such, perhaps you should consider not listing these specifically. (though
it will be in google etc + its not difficult for someone to find these if
they are curious)

> Sometimes you will see an odd code like AAEZ, this usually occurs if
> you are fed with TPON fibre and would need changing over to a copper
> line to get ADSL. As the copper isn't defined the database doesn't
> know how long the line is so puts Amber on both services.
>
> Tiscali, Plusnet and others offerring 150k or 256k speeds are doing so
> by using the standard BT 512k product and throttling it either at the
> exchange or elsewhere, so there is no distance advantage in these
> products, only a lower price.

Actually, the Tuscali/Plusnet offering's are normally provided via a 2MB BT
DataStream line not the 500K product and then throttled down. The prices for
the BT DataStream line are the same regardless of speed etc, so it makes
sense to provision as high as possible to make upgrades easier.

This can also lead to people failing to get a "150K" service though their
lines would support 512K etc

Regards
Sunil

On Sat, 13 Dec 2003 10:20:40 -0000, "Sunil Sood"
<(E-Mail Removed)> wrote:

>Actually, the Tuscali/Plusnet offering's are normally provided via a 2MB BT
>DataStream line not the 500K product and then throttled down. The prices for
>the BT DataStream line are the same regardless of speed etc, so it makes
>sense to provision as high as possible to make upgrades easier.
>
>This can also lead to people failing to get a "150K" service though their
>lines would support 512K etc

the Datastream ports are available at 512k, 1M and 2M. Why would the
service not be provided on the 512k version to give better coverage ?

or do they rent an ADSL port and just get the best speed on it that
the DSLAM and modem negotiate.

(they don't do my exchange anyway, so I can't use their availability
checker to test this out).

Thanks for the other comments, will incorporate them.

Phil

"Phil Thompson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Sat, 13 Dec 2003 10:20:40 -0000, "Sunil Sood"
> <(E-Mail Removed)> wrote:
>
> >Actually, the Tuscali/Plusnet offering's are normally provided via a 2MB
BT
> >DataStream line not the 500K product and then throttled down. The prices
for
> >the BT DataStream line are the same regardless of speed etc, so it makes
> >sense to provision as high as possible to make upgrades easier.
> >
> >This can also lead to people failing to get a "150K" service though their
> >lines would support 512K etc
>
> the Datastream ports are available at 512k, 1M and 2M. Why would the
> service not be provided on the 512k version to give better coverage ?

The wholesale price from BT for DataStream lines are the same regardless of
the (specified) speed they supply. (listed at
http://www.serviceview.bt.com/list/c...boo/120624.htm)

As such, it appears ISP's are asking BT to install/provision 2MB lines so
that the ISP can control the speed and (via capping) it makes upgrading the
end users to faster services easier as they don't need to involve BT (and an
additional regrading charge) then.

In theory, if a line is unable to support higher bandwidth services, the ISP
should resubmit the DataStream request to BT but for a 512K service
instead - in practice, I'm not sure this is happening though

Hence, customers can "fail" to get 150K but still get 512K lines.

>or do they rent an ADSL port and just get the best speed on it that
> the DSLAM and modem negotiate

You are describing RADSL there - that only applies to 512K lines..

Regards
Sunil

On Sat, 13 Dec 2003 14:22:45 -0000, "Sunil Sood"
<(E-Mail Removed)> wrote:

>In theory, if a line is unable to support higher bandwidth services, the ISP
>should resubmit the DataStream request to BT but for a 512K service
>instead - in practice, I'm not sure this is happening though
>
>Hence, customers can "fail" to get 150K but still get 512K lines.

I follow the argument, but why would someone selling a 150k service
want to exclude a fairly large proportion of the market that can only
get 512k ? There isn't any confusion sneaking in with the 2Mb PVCs
these people are using to backhaul the throttled service, is there ?

>>or do they rent an ADSL port and just get the best speed on it that
>> the DSLAM and modem negotiate
>
>You are describing RADSL there - that only applies to 512K lines..

not so, RADSL involves continual upstream rate shifting which is
different to what I was suggesting - let the modem and DSLAM figure
out what downstream speed the line will support *when they connect*.
This is common I believe in the USA where people see different link
speeds according to location. Maybe BT don't allow it, but I bet the
DSLAM supports it.

Phil

"Phil Thompson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I follow the argument, but why would someone selling a 150k service
> want to exclude a fairly large proportion of the market that can only
> get 512k ? There isn't any confusion sneaking in with the 2Mb PVCs
> these people are using to backhaul the throttled service, is there ?

No confusion no.

Its just what Tiscali (who are also behind Plusnet's service) appear to be
doing according to various reports - you are right about it not making sense
though.

> >>or do they rent an ADSL port and just get the best speed on it that
> >> the DSLAM and modem negotiate
> >
> >You are describing RADSL there - that only applies to 512K lines..
>
> not so, RADSL involves continual upstream rate shifting which is
> different to what I was suggesting - let the modem and DSLAM figure
> out what downstream speed the line will support *when they connect*.

Hmm - I was led to believe that RADSL in the UK is not a continual process
but only decided when the modem/DSLAM initially negotiates the connection.

However, as you say it is only in one direction (upstream) and not both as
in many other countries - though like you I am sure the equipment supports
it.

BT have done it for QoS reasons etc

Regards
Sunil

On Sat, 13 Dec 2003 10:06:40 +0000, Phil Thompson
<(E-Mail Removed)> wrote:

>The 4th letter refers to services on the line:
>
>A means the line has ADSL
>B or I are Home/Business Highway and ISDN lines
>E is a DACS line sharing device
>P means there are other incompatible services
>R means an order is placed for ADSL on this line
>Z means there are no incompatible products or service on the line

Mine comes back with a 'T' in the last digit. I have TPON, so I'm
assuming that's what the 'T' stands for?

On Wed, 17 Dec 2003 13:22:54 +0000, FryingVee <(E-Mail Removed)>
wrote:

>Mine comes back with a 'T' in the last digit. I have TPON, so I'm
>assuming that's what the 'T' stands for?

yep. I'll add it in. A lot of TPON lines got allocated AA?Z codes when
they decided to try and provide some copper, before that T was more
normal.

Phil