The alliance is seeking funding under the federal government's A$1.1 billion (US$850 million) Connect Australia program with members claiming its proposal is unique because its scale is national and the technology includes wireless, DSL2+ and fiber-based solutions suited to regional Australia.
The alliance will develop a coordinated business plan as part of its bid for funding while each company continues to build, own and operate its own networks and businesses separately.
Officials say Austar and Unwired's spectrum licences cover 95 percent of the population, enabling them to rollout low-cost, high-speed wireless broadband networks, while Soul has the largest independent regional access network.
It is a fully converged voice, video and data network with 280 points of presence as well as a capital city capability.
Austar CEO John Porter said the alliance can combine existing scale, scope and expertise to deliver the most cost-effective solution for Australia.
Under Connect Australia, Porter said IT Minister Senator Helen Coolan challenged industry to think big through partnerships and cooperation.
He said this proposal has a bigger broadband picture in mind, over and above individual commercial aspirations.
"The proposal is an opportunity to build the nation's first truly competitive alternate broadband infrastructure that will benefit all Australians," Porter said.
Austar has invested $50 million in a WiMax-based broadband network while Unwired expects to cover 45 percent of the Australian population with WiMax by 2008.
Unwired CEO David Spence said their networks are unique because they have been purpose built for data, voice and the high-peed services of the future.
"There are no legacy issues, no legacy dependencies, and no legacy costs; AUSalliance will go one step further by committing to deliver full broadband Internet mobility and national and global roaming based on the international wireless broadband standard - WiMax," Spence said.