So there's one in the cab, and one in the BRAS?

I don't have details of how they are deployed. The WBC one will be wherever it always was. The Openreach one could be anywhere - all it needs is real-time access to the DSLAM. Whether that means there is one in each DSLAM, or one at the exchange, or wherever, I don't know.

In reply to a post by RobertoS:

You actually have two DLMs operating there.

Hi Bob, happy New Year.

Two DLMs?... Then it's even more surprising they work . Given BT's DLM over ADSL was even more broken than the air conditioning on my new Land Rover I'm astounded they can get two working on FTTC/VDSL.
Clearly the very different line characteristics (much shorter lines but operating over a much higher frequency range) are easier for BT's DLM to handle (either that or 7+ years of their completely useless ADSLmax DLM has allowed BT Group to learn some very valuable lessons in how now to do things ).