According to Turnbull, the NBN was born out of frustration spurred by both governments' inability to meet a satisfactory arrangement with Telstra around upgrading its access network to deliver faster broadband.

He also reaffirmed his criticism of the government forgoing an independent cost benefit analysis of the project, a process he has .

"What remains most mysterious about the project is this: Every politician can understand the appeal of promising that all citizens will have access to very fast broadband," he said "But citizens expect politicians who make such a promise to do their homework and ensure that they deliver their promise in the most cost-effective manner."

"And yet this project, the largest in our history, has never been the subject of any cost benefit analysis.

"The government has not budged from its resolve and so there has never been any analysis, for example, of whether a fibre to the node deployment would be more cost-effective in brownfield areas, or of whether it would make more sense to continue the upgrade of the HFC networks rather than decommission them."