Hi FIOSCUST2012,
Don't panic. The battery is not necessary to the functioning of your services. The only time that the battery is even in use is when the power goes out and you need land line phone service. Other than that, the battery is useless. I agree that if you purchased services less than a year ago, Verizon should replace your battery for free. But you don't have to be in a rush. Unless you have a power outage in the near future, the only thing that the battery will do when you finally get it replaced is stop the ONT from beeping.
Hope this helps.