FiOS Phone - Determine if Your ONT has Power FiOS Phone - Determine if Your ONT has Power An Optical Network Terminal (ONT) is a small Verizon box generally located on the outside wall of your home. It has a power cord that goes into your home through your Battery Back-Up Unit (BBU)* where it plugs into an existing standard AC outlet.

Before performing the isolating procedure, you need to confirm that the ONT is receiving power. In the case of a power disruption, the BBU will provide power to the ONT if an active battery is installed in the BBU. Follow the steps below to determine if the ONT has power. You will need a flat-head screwdriver to open the ONT, and we recommend taking a flashlight and a copy of these instructions with you, if possible.

Note Although the lines are grounded, do not attempt to open the ONT or test the lines during rain, a thunderstorm, or other hazardous weather conditions. If there is a loud hum on the line, do not test the ONT. Call the Verizon Fiber Solutions Center. To determine if the ONT has power:

1. Locate the ONT and remove the screw that holds the ONT cover closed.



2. Open the cover and check the Power light.

If the Power light is:

• Green
  The ONT has power.
  Complete the test procedure for an ONT to determine if the problem is with the inside or outside wiring.


• Blinking
  The ONT is operating in Battery mode.
  A fully charged battery will power the voice ports on the ONT for up to eight hours during a power outage.


• Dark
  The ONT has lost power.
  If the ONT is accidentally unplugged, or in the event of a commercial power failure, it is possible that the battery is not properly connected or is dead. If you have not yet checked the Battery Indicator light or battery connection, check the Battery Back-Up unit.
  If the Battery Indicator light on the BBU is still lit or your service is still not working, contact the Verizon Fiber Solutions Center.

FiOS Phone Service may not be available in all areas.

Verizon Troubleshooter

You can use the Verizon Troubleshooter to diagnose your telephone's problem and request a repair if an issue is detected.

Watch the online Verizon Troubleshooter tour

Important Note The Battery Back-Up Unit is designed to use a 12-Volt 7.2 Ah SLA (Sealed Lead Acid) battery. Use of a different battery type 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. Batteries may be obtained at verizon.com/fiosaccessories or at a third party retail vendor.

See also: Related FiOS Phone Service topics