We had a land line for a while as it actually LOWERED our overall bill with Comcast, but we only ever had the fax machine plugged into it or used it to call our

We had a land line for a while as it actually LOWERED our overall bill with Comcast, but we only ever had the fax machine plugged into it or used it to call our missing cell phones. The problem I see about the emergency backup situation is that if we lost power for more than a few hours, our phone wouldn't work either because the battery backup would eventually die in the modem. The same was true of our old FiOS install at the last place (though the battery was much larger and not in the modem, at the fiber junction). So if you don't have an old copper phone line that doesn't need power from your house, what's the point of even having a landline 'in case of emergency'?