@kezo I didn’t even buy that kit, I just bought an RJ11 to BT cable on eBay for £5 to plug from my router to the old BT socket. I was under the impression the signal needed to be digitised and I’d need a special digital phone.
Glad you sorted it!
The Tel port on the router gives the same 48-50v and there’s no wizzardry involves however, not knowing much about Vodaphones router, I played safe but, the kit is more for if your existing bt socket were removed on fibre installation and with the modification shown in the link basically gives you, what you got now. The only digital is DECT insise BT’s fibre router.