Telstra Corporation Ltd 0400,0407-0409,0417-0419,0427-0429,04303-04305,0434,0437-0439,0447-0448,0457,0458,04590-04592Optus Mobile Pty Ltd 0401-0403,0411-0413,0421-0423,04301,0431-0432,04350 Vodafone Network Pty Ltd 0404-0406,0410,0414-0416,0420,0435 (except 04350),0449-0451,0424 Hutchison Telecommunications (Australia) Pty Ltd (trading as 'Three') 0424-0425,04300,04302,0433 Virgin Mobile (Australia) Pty Ltd 0466 (Note: Virgin utilises the Optus mobile network,and as such,other mobile operators (Such as Exetel) may also receive numbers in this range) Student Administration Pty Ltd 0488 Currently unassigned 0426,04306-04309,0440-0446,045 (except 0450 and 0458),046 (except 0466),047,048 (except 0488),049 However mobile number portability means an individual number might have been " ported". There are also many resellers,and many companies buy "air time" from other companies for roaming.