Sometimes that beeping is a false negative. So you can reset the unit and see if the beeping goes away, if it does then problem solved.
Now if it is bad, and does need replacing, then Verizon will send you one under two scenario's.
- You have had service less than a year
- You subscribe to their expert care service
If it's outside of a year, you are on your own, I found mine the cheapest at amazon.com search 12v 7.2ah f2 connector, sealed lead acid battery. Mine was about 15 bux plus shipping. easy to install.
If you want to avoid buying a battery completely, then you need to be relatively handy, and not afraid to pull a jumper, which is labeled Batt Alarm on the FiOS Service Terminal (ONT)
Just fair warning, the battery is for emergency phone use in the event of a power outage, so if you have phone service and you don't take care of that problem, then you will be without home phone when you have an emergency.
