How to Test Your FiOS Phone Line (ONT)
If you have determined that the ONT has power, the next step is to complete the ONT test procedure. You will need a flat-head screwdriver, a working telephone to connect to the ONT, a flashlight, and a copy of this procedure.
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. Contact Verizon Technical Support.
Check the battery back-up unit (BBU).
Related Troubleshooting Procedures topics
Go to the ONT and remove the screw that holds the ONT cover closed.
Open the cover and unplug the voice line that is not working and then plug in a working telephone (non-cordless).
There is no dial tone
You can use the Verizon Troubleshooter to diagnose your phone's problem. If the Troubleshooter detects an issue that it cannot solve, you will be given the opportunity request a repair.
There is a dial tone
The problem is with the wiring or jacks inside your home. You have the option to repair the wiring yourself, or you can have Verizon repair it for you. To make an appointment or to receive a quote for Verizon to repair your inside wiring, contact Verizon Technical Support.
Unplug the phone, plug in the voice line, close the cover to the ONT and replace the screw.