A group of telcos preparing an alternative to Telstra's proposal to build a national fibre broadband network are set to release the fine detail of their plan in a couple of hours.

The group -- whose members are likely to include AAPT, Internode, iiNet, Macquarie Telecom, Optus, PowerTel, Primus, Soul and TransACT -- are anxious to secure support from the government and regulators for their fibre network proposal, which is itself dependent on Telstra's involvement.

A press conference to launch the group's blueprint is scheduled for midday in Sydney.

Telstra is presently negotiating with the Australian Competition and Consumer Commission (ACCC) over the conditions whereby rival carriers would gain access to its proposed "fibre to the node" network, which would supply broadband at speeds of up to 12Mbps to some four million addresses.

While the ACCC has said it would also consider the rival plan, officials said reliance on Telstra's participation would constitute a fundamental weakness of the proposal.

The group has said already its plan would involve utilising the collective network assets of all telcos involved -- including Telstra -- to construct a fibre network that any supplier could use to sell broadband.

The proposed network would provide 12Mbps broadband to some six million addresses, and would take several years to build.