What happens to my nbn® service in a power outage and how do I replace the battery?

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    Your nbn connection needs power; without it your phone won’t work - not even for 000 calls. But there are a couple of cases where your phone will work in a power failure.


    Cordless phones need power and won’t work in a power failure regardless of your nbn connection. We recommend you have a mobile phone available in case you need emergency help during a power failure.

    If your phone’s still on the copper line

    If you have nbn Fixed Wireless and keep your home phone on the copper network, it will still work in a power failure if your handset doesn’t rely on mains power.

    If you’ve got nbn FTTP and a battery back-up

    If you have nbn Fibre to the Premises with a battery back-up AND a phone handset that doesn’t need power, your phone line should still work in a power failure for approximately five hours. During that time, you’ll be able to make and receive calls on a corded home phone connected directly to your nbn connection box.

    Replacing the battery in your nbn connection box

    The battery supplied during the initial nbn install has a two year warranty which starts when the nbn Battery Power Unit is installed.

    • If the battery needs replacing within the two year warranty period, Telstra will apply a $39 credit to your account and you can buy a new battery from any major battery supplier
    • If your battery is out of warranty, you’ll need to buy and install a replacement battery to ensure the back-up unit continues operating during a power outage.

    A list of battery suppliers and installation information is included in the Fibre User Guide provided by nbn at the time of installation, or in their battery back-up information.

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