On 03 Aug 2018 22:35:46 +0100 (BST), Theo wrote:

I wonder whether supplying every household with a power bank in your
router, which keeps the landline alive but also charges mobiles, might
not be infeasible?

AIUI the ONTs that convert the fibre to POTs and/or ethernet have
rechargeable batteries, either in them or the power supply brick. I
believe they are also user changeable and have a light to say "change
me" (not that people will pay any attention to that).

--
Cheers
Dave.