An answer to your post in the other thread on Optus market share:
In the Singtel annual report, FY 2012 (end March 2012), the report notes:
"In a highly competitive fixed broadband market, Optus registered a net gain of 18,000 on-net broadband customers in the year, bringing the total customer base to 978,000 as at 31 March 2012..."
A number of analysts, including the one quotes below, assess that Optus wholesale growth will continue to grow at the expense of Telstra:
"its (Optus) wholesale business had a market shift in 2011 and its growth suggests that, even with a subdued market, Optus’s overall share (of the Australian market) could surpass 23% by 2013."