I already had a bunch of Gigaset DECT phones, so I just swapped my base station out for one of these:

https://www.amazon.co.uk/Gigaset-N300A-Station-Answering-Machine-Black/dp/B0052RTG7O

For a while I had both the analogue line and the VoIP configured. Then, when we moved I dropped the landline. So it's VoIP only and nobody in the house knew anything had changed.

I tried using one of those analogue->VoIP adaptor boxes, but could never get the noise gate and echo cancellation stuff dialled in to my satisfaction.

In addition to the Gigaset units, I also have some Snom IP phones for the office/loft desks.