Also look at the VOIP services offered by the ISPs. Contrary to what Barry stated, I am with IINet not Telstra.
I choose their Naked DSL service and got my phone via VoIP, $69.95 (was 50G+50G, now 75G+75G) including the line rental. Free calls to landlines across Australia.
85min call Sydney to Adelaide $0
Last months phone bill $7.50. So far this month 652 minutes (including 30mins to NZ) $2.08, keeps the wife happy.