Search for Support

FiOS Phone - Checking the Battery Back-up Unit (BBU) In addition to your ONT, your service has a Battery Back-up Unit (BBU)* that is located inside your garage or house. In case your ONT is accidentally unplugged – or in the event of a commercial power failure – your back-up battery will provide you with power for voice service for up to 8 hours.

Your BBU was installed in a location in your home where it can be easily monitored. It contains a series of indicator lights that tell you whether your service is being powered by your home's electricity or the battery.

Please note that in the event of a power outage, your back-up battery will not operate your Internet service or router. Only your telephone service will receive power.

If you are experiencing trouble with your phone service, first check your BBU. The BBU light indicators are explained below.



BBU Light Indicators Your BBU has light indicators to signify certain conditions as described below:


AC Indicator: Green indicates that your BBU is operating normally. Yellow indicates the BBU is operating on battery power. If it is not lighted, check to see if the power cord is plugged in.



Output Indicator: Green indicates the BBU is operating on battery power. Otherwise, the indicator will be dark.



Battery Indicator: Red indicates that the battery is not connected or the battery needs to be replaced. Otherwise, this indicator will be dark.   If you are not experiencing a commercial power outage, follow the troubleshooting steps below. The light indicators explained above will help you determine if the BBU is receiving power.

1. Check that the power cord of the BBU is plugged into an AC outlet.


2. If your outlet is a Ground Fault Circuit Interrupter (GFCI), check that it has not been tripped. If it has, press the reset button.


3. Check the fuse or circuit breaker to make sure your outlet is working. Reset the breaker or replace fuses if necessary.


4. After taking these steps, re-check the AC indicator on the BBU to see if it is lighted. If it is, re-check for service.


5. If it is not lighted, contact the Verizon Fiber Solutions Center.

If you are experiencing a power outage and are experiencing trouble with your phone service, check the battery indicator on the BBU. Follow the steps below to check your battery.

1. If the Battery Indicator is red, check your battery connection inside the BBU.


2. If the Battery is properly connected but the light is still red, replace the battery in the BBU (see below).


3. After taking these steps, re-check the battery indicator light. If it is still lighted, call the Verizon Fiber Solutions Center.

If your light indicators are in normal status, complete the Optical Network Terminal test procedure. BBU Battery Replacement The average life of your battery is between 2 and 4 years, depending on the average temperature of the environment.

*Important Note The Verizon supplied battery is designed specifically for use with the Verizon FiOS Network. Use of a battery other than a 12-Volt 7.2 Ah SLA Sealed Lead Acid battery is not recommended since other battery types may impact the performance of your FiOS services. Verizon is not responsible for damages which result from use of an improper battery.When your battery does need replacing, you can purchase the 12-Volt 7.2 Ah SLA Sealed Lead Acid battery at major electronics outlets and home improvement stores.

Note Battery disposal standards and requirements vary by state. If you need to replace the sealed lead-acid battery in your BBU, please contact your local waste disposal resources for proper disposal instructions.

You can make a request for repair online

FiOS Phone service may not be available in all areas.

See also:Related FiOS Phone Service topics