Rickles:
I've noticed recently that all the ISP offerings include something like - " ... BYO modem, or modem rental $4 per month ..."
When talking about pure fibre, surely the 'modem' is the ONT/box (router) on the inside wall?
Are they using modem and router interchangeably (and confusingly) 😆
Just to be a devils advocate, if the router has RJ11 ports for a telephone would not it contain a modem interface for that to work ?.
But you can also connect phones to the ONT which is a modem.