In the event of a power outage, your home phone service will not work unless there’s a battery back-up connected to the Fibre Hub. The battery allows your phone service to function during a power outage, including calls to 911 and connected home alarm systems. A fully charged battery can last between 4-8 hours, depending on usage. Cordless phones won’t function during a power outage. FYI: Batteries are sold separately, or you can purchase one from a third party. It’s the customer’s responsibility to replace the battery when necessary.