We have a copper landline with broadband router. Sometimes 10mbps, often less, but quite adequate, we don't do streaming or gaming and it's fast enough for Skype and surfing.
The mobile signal here ranges from poor to non-existent and these are rarely used anyway. We're with Giffgaff PAYG for mobiles and Plusnet for broadband/phone.
Sooner or later we're going to have to change to fibre. Giffgaff don't do Wifi calling, and Plusnet don't do phone over internet, or whatever it's called.
Also, we'd like to keep our 'landline' number.
There's a lot of sometimes contradictory information, but I reckon someone must have achieved what we want to achieve, ie same phone number and same service providers.
Is that person among you?