Battery back-up information for Fibre to the Premises

In the case of a power outage, the battery back-up will last up to approximately five hours. If your back-up battery is flat, faulty or missing, your phone and internet services will not work. You will know when it's time to replace the battery when the "Replace Battery" light appears on the nbn™ connection box. You will also hear an alarm sound - one beep every 15 minutes indicates the battery needs replacing, and four beeps every minute indicates less than half of the battery charge is remaining.

The NBN battery is solely the use within the lot and is therefore not common property.
A new battery can be procured from Jaycar audio for a small fee.
For instructions on how to replace the battery please see the link below.
https://www2.nbnco.com.au/learn-about-the-nbn/network-technology/fibre-to-the-premises-explained-fttp/battery-back-up-service-information.html
 
to purchase the battery contact:
https://www.jaycar.com.au/store/Alexandria_JaycarAU?lat=-33.86651&long=151.20945&q=Sydney

see attached battery specification to show Jaycar which battery you need.