The Optus $0 plan is not by itself a great plan, but it is free and an Optus representative has informed me that it's eligible for the $20 mobile bundle discount with a broadband plan.
$0.10/MB, charged per KB
62c/min + 35c flagfall, charged per min, 2min call = $1.59
sms/mms 10c
$0 Optus Plan: Available for new services until 3rd July 2016. This plan does not include any calls, text or data and any usage is charged according to the rates outlined in the Critical information summary document. This plan is not eligible to data pool with eligible mobile or mobile broadband plans.
Calls to standard Australian mobiles and landlines, 13/1300 numbers and Voicemail. Standard International SMS 50c per message up to 160 standard characters, Standard International MMS 75c per MMS
Where is the $0 comes from? The web site shows $30/month…