Usually not.
You'll find that a lot of mobile phones sold here legally do not bear an AS/ACIF S043 sticker (the "A-Tick") because the phone's
GSM chipset is one that is already approved ... technically, the manufacturer / importer of those phones are breaking the law, but because the bit that does the actual connecting has already been approved by the ACMA, they tend too be lazy gits and not worry about it.
There are some GSM chipsets -- from Korea and Japan especially -- that have had the spec tweaked, or some localised speciality added. These phones
may work on our networks, but they will not pass approval.
From
http://www.acma.gov.au/WEB/STANDARD/pc=PC_1784:
"Q: I have lived or travelled overseas - can I use the GSM mobile phone I purchased overseas in Australia?
"A: A mobile phone (for personal use) may be brought into Australia and connected to a mobile telecommunications network provided the phone meets Australian standards. If you are travelling and plan to purchase a GSM mobile phone overseas, ACMA recommends that prior to departing from Australia you contact your mobile carrier to find out what mobile phones are suitable for use in Australia. Some features on certain models of mobile phones purchased overseas may not work on the Australian mobile networks."
In other words, if the bought-overseas phone uses a GSM (etc) chipset that has already been approved for use by the ACMA, you can use it
provided it is bought by you, overseas, and is not for resale.
So, technically speaking, the person behind that original shitty advert is breaking the law.
B.