So you are probably on Livebox Zen and are out of the 12 month discount period which means you will be paying 33.99€ (+ 3€ if you have the TV box) or on Livebox Play but still within the 1st 12 months in which case you pay 34.99€ which is going to go up to 39.99€ after 12 months.
Obviously you do pay for the copper pair to be provided within the above fees.
Yes, I considered going down the VOIP route with Orange, it is a bit cheaper as retaining your "ligne fixe" amounts to an extra 12,96€ per month.
However the original game plan was to run everything VOIP and provide a UK number for the house, as well as a French number and also allowing any renter a limited amount of phone use. All of that needs a custom SIP or IAX server and dial plan. Unfortunately that would not play so well with using the Livebox modem so keeping the phone line meant that I could use my own gear - which I did when I briefly had ADSL. Switching to VDSL stopped that at the time - I now know the configuration needed to get VDSL and the TV box working with a 3rd party modem but just haven't had the time/energy to sort it. Too many other jobs around the place. I'm also going off my original plan for various technical and economic reasons but haven't quite formulated a plan for how I do want to set things up.