From Guardian Project Wiki
VoIP access in Australia is widespread, [www.acma.gov.au/.../main/.../changes_in_australian_voip_market.pdf with over 250 providers as of 2009] according to the Australian Communications and Media Authority (ACMA); in the recent Ipsos survey, 10% of users surveyed had used VoIP services within the last three months. According to the ACMA, VoIP providers are considered Carriage Service Providers (CSPs) under Australian law, and are regulated by the Telecommunications Act of 1997 and the Telecommunications (Consumer Protection and Service Standards) Act of 1999.
While the Australian Internet content filtering regime is quite restrictive vis a vis comparable countries, the widespread provision of VoIP services has not been deterred - for instance, the number of Australian Skype users increased from 876,000 unique users to 1.01 million unique users between June 2008 and June 2009, according to the ACMA. Among the requirements VoIP providers are subject to by law are provisions relating to "public interest obligations," including "Law Enforcement (interception and national interests)." It is unclear how VoIP services might directly be affected by these provisions, though at minimum they allow warrants for the collection of IP addresses and other UDIDs.