
The OP's brother is ona WBC-enabled exchange so XRaySpeX's description of the DLM is correct. You appear to be on non-WBC, which is unfortunate for you.
Given the WBC almost invisible DLM, which on a stable line will lower the sync-time margin to 3dB from its default 6dB, the TT default 9dB looks a bit underwhelming.
I had my doubts when XRaySpeX first started saying this sort of thing, but nearly all Orange stats I have seen since are very good compared to previous Orange LLU. He seems to have "the facts" on his side.
The question is anyway almost irrelevant to this instance.
Unforgivably those that have access to LLU and BTW 21CN , FTTC and cable forget that large parts of the country are still on BT non standard ADSL and my best hope of having ADSL2+ is rather with TalkTalk enabling my exchange as they already have more ADSL2+ equipment in exchanges than BT do and are still doing more small exchanges even as i type this .
So local to me , most of the larger villages now have TalkTalk equipment in and no BT21CN equipment , in fact one exchange did have Orange LLU but no BT21CN but luckily Sky and TalkTalk had LLU equipment there and BT did 21CN the exchange but not after losing Oranges customer to other providers .
TalkTalk default line profile is 12db and often gets reduced to 6db by there version of DLM that strangely is not normally active or used as a training period but seems to randomly do its work if it appears at all .
But i have to admit i was not aware of BT 21CN DLM and how it worked and thank your self and XRaySpeX for bringing this to my attention but that does not change the fact there are more TalkTalk LLU exchanges than BT21CN exchanges , allot more !
As you say thou " question is anyway almost irrelevant to this instance " and i agree and will now desist with taking this topic of track .
Edit: not forgetting Isfield that is local to me and has no broadband provision at there exchange and sits between two market 3 exchanges . So i don't feel bad about not having ADSL2+ but lucky to have broadband .
Edited by deleted (Tue 28-Aug-12 18:45:17)