The FCC has voted to require facilities-based fixed-voice services providers -- including cable operators -- to offer backup power options at point of sale, though backup power is not mandated.

The move is part of the IP tech transition from copper-based phone service that had its own power source and did not go down when the power goes out.

Carriers must initially provide an 8-hour backup option, with a second, 24-hour option, offered after three years.

Providers must offer installation, and must annually notify subscribers of the availability, and limitations, of the options; notifications are to include information on needed maintenance and use, self-testing, warranty details and more.

Carriers will have flexibility on how to provide that notice, the FCC said.