"The difference is in the revenues. It adds a lot to total funding requirements,'' senior telecommunications analyst at Ovum, David Kennedy, said. He believes a fibre-to-the-premise network would take even longer to roll out than the strategic review's estimate of 2024 completion, but that the figures in the latest report were more accurate than previous estimates. "A lot of the assumptions that were made three years ago have been proven to be false. Now we have three years' experience of what NBN is actually like,'' he said. The strategic review found the cost of building and operating a fibre-to-the-premise network over eight years would cost $58 billion compared to $57 billion for a mixed-technology network. It estimates it could finish off the rollout started by Labor for $44 billion – about $7 billion more than the $37.4 billion previously estimated. It also estimates a fibre-to-the-premise network could be done for $35 billion through more efficient construction techniques, better use of labour and less materials. However, the finer details of how that would be done were blacked out for commercial reasons.

But the NBN Co board has recommended the government instead change the rollout to a mix of technologies that will cost about $30 billion to construct. This mixed bag would see about 2.9 million houses or businesses with a fibre-to-the-premise connection, 3.6 million with a fibre-to-the-node connection and 3.3 million using the existing pay TV cable connection. The type of connection all depends on what type of cable or line already runs past a house. It warns that annual maintenance and operating costs for the older technologies were about $4 billion higher over ten years. Operating costs for fibre-to-the-premise were $9 per premises per year, compared to between $35 and $55 per premises per year for fibre-to-the-node connections and $15 to $25 for premises on the hybrid fibre coaxial [HFC] cable network. These figures did not include the cost of renting infrastructure from Telstra. The mixed-bag network ends up costing $27 billion to operate over eight years compared to $23 billion for fibre-to-the-premises. "Given fibre-to-the-node utilises existing copper for last-mile network, significantly more ongoing maintenance is required, and allowed for in the modelling conducted by the review. Fibre-to-the-node variable operating expenses are estimated at $35-55 for the access network per brownfields premises passed per year, including $10–20 for electricity and $25-35 for corrective maintenance,’’ the review found. But, hidden within the report is also the astounding news that 90 per cent of annual operating costs would be money flowing to Telstra and Optus, thanks to the deals signed by NBN Co over the past few years. Telstra gets the bulk of the money becuase NBN Co needs to rent so much of its infrastructure. So the bulk of operating costs won't change even if broadband technology becomes cheaper to operate. But operating costs could also go higher if Telstra demands more money from NBN Co for using parts of the copper network, which is not part of the existing deal.

But what about the funding estimates of $73 billion, $64 billion and $41 billion? These estimates are based on how much money NBN Co and its consultants think will be needed before sales revenues start covering both annual operating costs and the cost of construction. And the earlier NBN Co can connect to houses and businesses the quicker it can earn revenue. Therefore the strategic review estimates NBN will be profitable sooner if it does a quicker and cheaper mixed-technology infrastructure upgrade rather than the full fibre replacement rollout. Hence the difference in funding requirements. The Labor government was too attached to the fibre-to-the-premise roll out, according to telecommunications analyst at CIMB, Ian Martin. "This government has inherited [NBN] and is not necessarily committed to a single technology. It wants to achieve something in terms of high speed broadband [but] is not as driven to have fibre to the premises at all costs, but rather looks at the most effective way to deliver its target by 2019." The proposed cost of building a national broadband network has changed every year since the project was first announced. At least seven consulting firms have been paid handsomly to provide their expert opinion on whether NBN Co can be built, for how much and in how many years. Some reports have been made public, some have been kept confidential, and some have been released but with key details blacked out.

The one thing these reports all prove is that forecasting huge decades-long projects is very difficult and the conditions keep on changing. Given most Australians don't even understand the technology and infrastructure hurdles that prevent them from getting faster broadband today, it is no wonder they find NBN Co's changing story confusing and frustrating. Most of these broadband-hungry people are not ideological and do not care if government or the private sector owns the infrastructure. They just want someone to build something that works well for a long time. For the moment, we still don't know what the new government is going to do because it hasn't responded to the review yet. It has two more reviews under way which will no doubt inform its final plan. "The advice contained in the strategic review will be a crucial input into government policy, setting out as it does the facts on the current NBN and realistic and informed analysis of options to vary its design and delivery,'' a spokesman for Mr Turnbull said on Wednesday. And so we wait.