Do I call for service or am I expected to replace a battery myself?
You can buy the battery cheaper at Home Depot or Lowe’s or from an online retailer.
or you can totally disable it and never worry about it again. The BBU is for phone service. If you have phone service and you lose power the unit will keep the phone on for up to 8 hours.
However if internet only or internet & tv then just follow the instructions to disable it permanently. Follow instructions from here. https://www.verizon.com/support/consumer/battery-backup