What is MaxDSL?

"MaxDSL" or more correctly DSLMax is a new range of products that are available from BT Wholesale in April 2006. It is not a new standard of adsl, but does have a few differences to the traditional adsl we may be used to.
The first being that as well as increases in downstream speeds, upstream speeds will also get a boost.
The most important difference is that the maximum speed that you will be able to get will be "rate adaptive".

What is the DSLMAX product set?

Product	Old Contention Ratio equivalent	DownStream Speed	UpStream Speed
BT IPStream Max	50:1	288kbps - 8128kbps	64kbps - 448kbps
BT IPStream Max Premium	20:1	288kbps - 8128kbps	64kbps - 832kbps
BT DataStream Max	ISP set	288kbps - 8128kbps	64kbps - 448kbps
BT DataStream Max Premium	ISP set	288kbps - 8128kbps	64kbps - 832kbps

How does DSL Max differ from traditional ADSL?

Traditionally the maximum speed that we are able to achieve is set on a BT database which is loosely based around the length of lines and distance from the local exchange.

As has been shown in the past, this database can be wrong, and lines that may be able to get 2Mb speeds have not been able to do so simply because the database is wrong. Conversely the opposite has been found to be true and some 2Mb lines have had to be downgraded to 1Mb or 512kb to maintain a stable connection.

MaxDSL does not work like this, instead new equipment in the exchange will be able to monitor your connection and ensure that you get the best reliable speed.

Its not unknown for some lines to sometimes be able to support better speeds, but something such as a change in weather can cause a connection to become unstable.

What does Rate Adaptive mean?

That your maximum connection speed is determined by the quality of your line. Since line quality can vary over time, special equipment (RAMBO) installed in the exchange is used to monitor your line performance and adjust the connection speed accordingly whilst on maxDSL.

According to BT, the actual line rate supportable will be determined during the first 10 days of use, after which time the highest stable rate possible will be set.

Users downstream speeds will be between 256kbps* to 8Mbps with increments being in 0.5Mbps increments in between these two figures. Upstream speed increments are 32 kbps.
*The downstream will actually go as low as 160kbps, however this can be reported as a fault, and BT will try and bring the line back up to a minimum of 288kbps.

See here for How MaxDSL Works

Is there any way I can find out what speed I am likely to get?

Unfortunately until you have the service you wont know exactly.
The BT checker should give you an indication of what BT estimates your line will be capable of. (From experience this figure is sometimes on the conservative side.)

The site has a Maximum Speed Estimator for DSL Max & ADSL2+ here
Mr Saffron from thinkbroadband has also produced a good "guestimator" which estimates your maximimum line speed based on your current line stats here.

News Archive

10 November 2005
ADSLguide News Archive - BT publishes details of the forthcoming Max beta trial

31st March 2006.
Max goes live.

The BT checker should give you an indication of what BT estimates your line will be capable of.
All exchanges which are to be maxdsl enabled are now "live". Exchange status can be checked from the Plusnet User Tools site.
Your line will not automatically be upgraded as this is down to the individual ISP's submitting your line for upgrade. This process may take several months to be completed.

BTWholesale Bulk Speed regrade process.

MaxDSL should not be confused with the ongoing/recent BTw Bulk regrade process.
The Bulk speed regrade process is whereby an ISP has paid BTw a fee to upgrade all their customers connections to a maximum of 2Mb if their line can sustain it.
This project is a fairly mammoth undertaking as millions of lines are being upgraded.
This process is costing ISPs a fair bit (£5+VAT per customer) but its still much cheaper than doing it on an individual basis (£11.00+VAT).