On Openreach FTTC, (GEA), an ISP may impose its DLM on its own network, as BT Wholesale does to provide their IP Profile. Sky may well have some similar system, and TT too.
But none of the three can directly set the SNRM. End of!
They can request Standard (apparently 6dB), stable (9db?) or super-stable (12dB?).
Then there is a prioritisation system they can invoke wrt the traffic on any given user's line, but all that does is play with the way the bandwidth available to that customer is divided up between that customer's applications - VOIP, streaming, etc. They cannot prioritise one customer over another
on the GEA service. Once it is handed over to them at the exchange, then of course they can do whatever they like.
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost.
Internet connection - Plusnet Value Fibre FTTC 80/20 trial.
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~