You can't use an ATA as Telstra do not provide the SIP password required for it to work.
What you could do it connect the WAN port of the Gateway Max to the LAN port of the D7000, but disable NAT, DCHP and wireless on the Gateway Max before doing this. Your phone will still work with the Gateway Max in this configuration.
So the network would look like this:
NTD==>D7000==>Gateway Max==>Home phone