Fixed line telephones connected to the NBN no longer use the traditional copper network and use Voice over Internet Protocol (VoIP) as the connection medium into the telephone network, a data connection.
All the calls go through the modem connected to the internet which is powered by a connection to the site/house power. If the power to the house or the modem is off, this fixed line phone will also be off and not work. Therefore Emergency Alert messages to the phone will not be received.
What can you do?
You can purchase a backup power supply for the modem which can be arranged through the internet provider. This will be a battery device that will provide power for a fixed period of time during the power outage.
Talk with your internet provider.