Co-author of the report and director of CIE's Sydney office, Kerry Barwise, said Telstra is hiding the truth about how much it will cost to build the NBN, and how much they intend to profit from it.

"This is going to be the single largest public infrastructure investment in Australia in the next two decades at least, and it's so important that it be in the open," Barwise said.

"If the numbers are bogus it's because the CEO of Telstra hasn't told us the truth about how expensive it's going to be and how much extra he really wants. If it's bogus it's because when they say "north of 18 percent" they mean substantially more than 18 percent."

Barwise defended the independence of the CIE's report and dismissed Telstra's claims that it was intended to slow or disrupt the broadband process.

"We're evidence-based. If Telstra put the cheapest offer on the table I wouldn't hesitate to tell the CCC, Terria, Optus, Macquarie Bank or anybody that 'look, you guys are fooling around, stop wasting your time and let Telstra get on with it'.

"But the evidence doesn't suggest that, the evidence from Telstra is that they want more money than the other guys," he said.

Also at the event was communications analyst/economist for the Organisation for Economic Cooperation and Development (OECD), Dr Taylor Reynolds, presenting "Fibre Investment Challenges and Opportunities" and an overview of broadband penetration in OECD countries (see slide).

Talyor's presentation showed that use of bandwidth caps is growing, with two thirds of OECD countries adopting quotas at an average of 15.6GB for DSL, 28GB for cable, 14.4 GB for wireless and 85GB for fibre connections. Australia's average cap across all connection types is approximately 15GB.

But Australian consumers are slugged with by far the highest download rates once that bandwidth cap has been exceeded. Ranked 6th out of the top seven countries consuming the highest average data cap, Australian consumers are charged more than five times the rate of the other six countries per extra MB (see slide).

Forman said the fact that Australia has data caps relative to the rest of the world, but with such an exorbitant price once that cap is exceeded, is indicative of excessive market power.

"If it was possible for other people to provide more attractive pricing, then Telstra would have to respond. But they are able to get away with this because they have so much market power, so much control over costs of transmission of data.

"Everything from the end user access to the international connections have, over the years, been identified as being problematic. Telstra has a degree of market power that creates pricing that is excessive compared to other markets."