Except for the tiny percentage of new fibre lines in a few cities, all landlines that run to our homes are either Openreach or Virgin Media cable. Plus Kingston and Hull which has its own system, or did.
Virgin Media is a case on its own as its lines only support itís own broadband.
Sky, TalkTalk, Vodafone, Uno, IDNet, Zen and all the others use Openreach lines at least to the exchange, That includes FTTC, FTTP and ADSLx. Most ISPs use BT Wholesale (controlled) services on the fibre and copper lines. The LLU Suppliers control the Openreach copper lines that they use, but not really the FTTC and FTTP lines between us and the exchange.
Zen are a sort of half-way house between BT Wholesale and LLU as far as I can tell. IDNet use some BT Wholesale and some Zen services. But all those lines are Openreach as far as the exchange, both copper and fibre.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - Three 4G, tbb tests 35-45Mpbs down, 9-15 up.
If you never think of anything off the wall, you'll never think of anything original.