No. This is a simple wireless router that has an option for a WAN port and or a SIM CARD LTE/4G. So if you have FTTN (VDSL2) as your NBN you will need a vdsl modem. This router has provision for VOIP and or uses LTE voice from your 4G SIM. But you will need an Analog old style pstn phone connected at the rear of this router.
Hi, this modem can use for NBN FTTC, FTTP, FTTH and HFC. Not For FTTN/FTTB.
and yes, if you use for above support type of NBN connection, then the 4G can be use as back up.
As long as the NBN connection is up, the 4G LTE connection will stay as back up.
If NBN connection is down, the 4G LTE will automatically comes up within 15 seconds.