2 years data retention
That looks like metadata (see https://www.homeaffairs.gov.au/nat-security/files/dataset.pd..., PDF warning). Which is still private, but doesn't include your private calls and messages.
How long do they keep private calls and messages?
7-10 years, in practice. 2 years, in requirement. [0]
[0] https://www.aph.gov.au/About_Parliament/Parliamentary_Depart...
> … is not defined in the TIA Act but is generally understood to refer to information about a communication that is not the content or substance of a communication.
I'm asking asking about content.
> ...
> There are two types of preservation notices—domestic (‘which cover stored communications that might relate either to a contravention of certain Australian laws or to security’) and foreign (‘which cover stored communications that might relate to a contravention of certain foreign laws’).
> In turn, there are two types of domestic preservation notices—historic (‘which cover stored communications held by the carrier on a particular day’) and ongoing (‘which cover stored communications held by the carrier in a particular 30-day period’).
> A foreign preservation notice only covers stored communications held by the carrier on a particular day. The Ombudsman and the Inspector-General of Intelligence and Security will have oversight in relation to preservation notices.
Preservation notices are incredibly rare, and no drag net requirements exist in Australia. CSPs are free to store such things, but generaly don't - beyond required metadata.