Broadband Extension Technology (BET) has been touted by BT as solution for rural long-lines, using G.SHDSL equipment tuned to run an impressive 12km at 1Mbps.
BT are keen to promote this as one of the options of fulfilling the old government's 2Mbps universal service promise but it doesn't seem to make sense.
This isn't rocket science - if you can get 1Mbps out of a copper pair then all you need to do is run two pairs side-by-side and you'll get 2Mbps.
But my personal experience is that copper pairs aren't that abundant in rural areas. We're talking about miles of cable strung along poles - weight and cost were big issues in these deployments, and there was never a reason to put spare capacity in.
So BT will need to install a second pair to a give 2Mbps using BET.
In actuality, BT may have to run this extra pair if they are going to deploy BET at all, even at 1Mbps, since G.SHDSL doesn't co-exist with voice service on the the line.
The obvious question is, why not just run fiber and be done with it?
Sometimes, just because you can do something isn't a good enough reason to do it. BET might be the wrong solution for most customers.