In the letter the AAB, which includes telcos Vocus Communications, EFTel, AAPT, BigAir and Pipe Networks founder, Bevan Slattery, urged the Senators to heed its call, stating that each of its members had different things to gain and lose under an NBN.
"Some have dismissed our views lightly as being self-interested, even though credible national and international voices have recently expressed their own doubts or criticisms of the NBN proposal," the letter reads.
"We welcome this debate and are excited to have helped to generate it. We now believe it is time to have a credible, independent, dispassionate and rigorous analysis done of the NBN proposal."
While supportive of the need for a national broadband capability, the AAB stressed the Senators' need to ensure the Government's policy was sound and that taxpayers' money was spent well and wisely.
"...Policy of this magnitude which carries with it fundamental changes to the entire fabric of the national telecommunications landscape and re-creates a new government-owned monopoly requires Members of Parliament to ensure such a policy is the best policy for the future development of the country, and in particular the delivery of the most efficient investment by the Australian taxpayer," the letter reads.
"Past delays cannot justify panic or cut corners now. Mistakes we make in the design and/or policy settings for the proposed NBN, particularly in the areas of structure, affordability and accessibility, will not be easily fixed down the track and could be disastrous for our international competitiveness."
According to the AAB, allowing the Productivity Commission to assess the Federal Government's NBN proposal would inject facts into a broadband debate where they were otherwise missing.
"The NBN proposal now differs significantly from the proposal that was contemplated in the Implementation Study (which already found that the proposal in its then form was unlikely ever to generate a commercial rate of return)," the letter reads. "No serious analysis has been done of the changed cost implications of those differences. Fundamental features of the project remain unresolved."
The letter also echoed Opposition communications minister, Malcolm Turnbull's that the NBN Co's plan to limit the number of points of interconnect (PoI) on its network will "strand" hundreds of millions of dollars of existing private investment in fibre links.
"NBN Co's suggestion that it would prefer a small number of Points of Interconnect nationally has been met with almost universal opposition from the industry, will strand billions of dollars in private investment and thousands of kilometres of optical fibre, and lead to network inefficiencies."
The open letter is the second the AAB has issued on the NBN, , in which it claimed the argument for a national fibre-only NBN solution had failed to convince.
In September, the AAB said The Alliance of Affordable Broadband (AAB) its campaign to convince the Federal Government to modify its plans for the National Broadband Network (NBN) would achieve results.