About 5 years ago my parents, who've always had a proper hard-wired copper landline phone contacted AT&T and asked for faster internet at their home. What the phone company did was to install a new modem in their house with 2 different jacks on it. 1 of those jacks now feeds their phones and the other feeds their internet service. When they had a power failure shortly after that modem had been installed and they lost power, their hard-wired phones went out as well. When they called AT&T to complain and explain they wanted a hard-wired landline phone that was always live and they didn't want their phones running through a modem, they were told it was too late, they could not go back to a hard-wired copper system even if they cancelled their internet service, that AT&T was removing copper systems and as a consolation, AT&T sent over a service tech with a small UPS to power the modem for a bit after their power fails...But once the UPS dies, so do their "landline" phones.