Directing NBN Co to switch from Labor's model for fibre to the premises to the Coalition's proposed multi-technology mix without first awaiting the results of a cost-benefit analysis will allow NBN Co to get on with its job, according to Communications Minister Malcolm Turnbull.

In his time in opposition as communications spokesperson, Turnbull derided the then-Labor government repeatedly for failing to complete a cost-benefit analysis prior to embarking on its AU$37.5 billion fibre-to-the-premises project.

After returning to government in September last year, Turnbull committed to conducting a cost-benefit analysis into broadband in Australia, and appointed Michael Vertigan and a number of other experts to conduct the analysis with a report due back to government in June.

Turnbull left the door open that if the report finds that the benefits of fibre to the premises balanced the costs of such an endeavour, the government would consider keeping the existing model.

But it appears the government will proceed with its own version of the NBN without waiting for the analysis.

Since September NBN Co has continued its existing work on the fibre to the premises rollout, but in a new statement of expectations released today , ahead of the Vertigan panel's report, Turnbull directed NBN Co to commence work on a multi-technology mix model that will allow NBN Co to deliver at least 25Mbps downloads to all Australians with a maximum of government investment of AU$29.5 billion.

Despite years of sledging Labor over its decision not to conduct a cost-benefit analysis before proceeding with the NBN, the decision to proceed with his preferred model for the NBN despite the cost-benefit analysis not being completed was prudent, Turnbull said, adding that the statement could be changed down the track.

"The company has got to get on. It doesn't mean there won't be a change to it. There have been a number of statement of expectations already," he told journalists at the CommsDay Summit in Sydney today.

"The key point is you have the freedom to use the mix of technologies that suits the particular locations.

"The whole purpose of renegotiations with Telstra is we want to put NBN Co in the same position and flexibility and optionality it would do if it was the incumbent, instead of being locked into one very slow, and very expensive technology."

Under the new statement of expectations, NBN Co will now be able to determine, area by area, the most cost-effective technology to meet the minimum speed requirements for the NBN.

Prior to the election, the Coalition promised that all Australians would have access to 25Mbps download speeds by the end of 2016, and 90 percent would have access to 50Mbps down by the end of 2019.

In the statement of expectations, the timing for delivering on these promises is removed completely, except to say that 50Mbps should be delivered "as soon as possible".

In a speech at CommsDay Summit this morning, Shadow Communications Minister Jason Clare said that Prime Minister Tony Abbott and Turnbull should be held to account for breaking this promise.

"The government announced it was breaking [its promise] just before Christmas — the day after Holden announced it was pulling out of Australia," he said

"This is a serious breach of faith. The people of Australia might not have liked their NBN plan, but they were told they would get it by 2016. They won the election and then broke their word. And they should wear the consequences of that at the next election."