FttP and VoiP

What ho one and all,After three months of faffing around, Openreach orders created then cancelled, three cancelled engineer visits and one visit who only managed to find problems (small branch hanging across the pole, no survey to ensure there is no gas/elec/water in the apex where the current phone line enters) yesterday, finally, an OR engineer with common sense managed to fit the fibre, ans as she described the job to a colleague, it was 'p*ss easy!'The original copper has been removed and apparently, EE will assign a temp phone number before moving my existing number to the new service. One phone is plugged into the router and give a 'no number on this service' message, which is fine. Have plugged the supplied Home Phone Adaptor into the 13a but it is not syncing with the router; perhaps that is because there is no connection yet. Time will tell.However, although there is no copper connection to the outside world, all the BT wiring and Master Socket is of course,still in place. Is there a way to connect extension phones to the router using the existing wiring rather than relying on a wi-fi signal? In other words, can the extension phones be plugged into the BT wiring as normal and the Master Socket connected directly to the router with the RJ11 socket?Thanks and toodle pip