I could be wrong on this, but Im sure BT retail already offer this as a service. Ive seen someone post on a forum a couple of months ago about this and how they were on a long D side and because their VDSL speed was less than 'x', BTr had put them on a special product and they get charged accordingly.
Would that be something like "Total Broadband Option 3 with Fibre", or "Faster Option 3 with Fibre"? I recall BT Retail introduced something like this a few years ago, when they had a strict minimum threshold for the Infinity product line of 15Mbps; at the time there were 2 options within the "standard broadband" product line (hence the "option 3" part), and there was no such thing as "Infinity 2" as 80/20 hadn't started at the time.
There were the usual screw-ups when the product was first made available (sales reps mistakenly ordering a standard ADSL-based product instead); once sorted, it looked like subscribers were treated identically to Infinity subscribers after the order. They had engineer installs, with SSFP and the standard Openreach modem.
BT retail would make the discrimination based on the estimate, so (of course) some people got considerably higher speeds than estimated - and I recall seeing some actual download speeds higher than 30Mbps. That would preclude the use of any form of ADSL2+.
Unfortunate that we were subject to locked-out modems, as that means we have little evidence of what these people actually synced with.
ISPReview has this old story:
http://www.ispreview.co.uk/story/2011/07/01/bt-launch-uk-faster-total-broadband-option-3-deal-for-sub-15mbps-fttc-lines.htmlThe SIN also specifies that the modem has to support SRA and PHYR (G.INP).
That has definitely been there for a while... because I quoted some of SIN498 to TPLink a while back and it was one of the requirements I noticed when I sent them the link to an earlier version of SIN498.
True - though those requirements were a subset of the whole set for VDSL2 modems, including the vectoring ones.
The section I read (and copied those requirements from) were specifically for the "GEA over ADSL2+" modems, so didn't include anything like vectoring. I thought it was worth noting, because we don't see either SRA or PHYR as part of today's DLM for ADSL2+ (which would be BT Wholesale's DLM); it gives another suggestion that BT Openreach's DLM may be headed in a new direction.
For the sake of completeness, the test specification does include tests with FEC and interleaving turned on (a lower variant with 1 symbol of INP and 8ms delay, and a higher variant with 2 symbols of INP and 16ms of delay) - so we should expect those to continue. Conversely, all profiles mentioned had a fixed 6dB target margin - suggesting that we would not see the Openreach DLM performing stepwise increases of the SNRM to 9, 12 or 15dB even on ADSL2+.