The Australian Competition and Consumer Commission has accepted the varied Special Access Undertaking (SAU) lodged by NBN Co on 19 November 2013.
The varied SAU incorporates all of the changes in the ACCC's notice to vary and replaces the undertaking submitted by NBN Co in December 2012.
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The SAU will form a key part of the framework for governing prices and other terms upon which NBN Co will supply services to telecommunications companies over the NBN until 2040.
ACCC chairman Rod Sims said the acceptance of the SAU was a key milestone in establishing regulatory arrangements for the NBN.
"It is part of a broader set of regulatory and structural reforms that have occurred across the industry in recent years," he said.
"The SAU will form the basis for how NBN Co can set its prices and change its product offerings over time. It will also form the basis for ACCC oversight of NBN Co's allowable revenues and prices."
The SAU will operate until June 2040.
The decision to accept the SAU follows two years of extensive consultation and assessment by the ACCC.
In April this year, the ACCC released a draft decision indicating that the SAU submitted by NBN Co in December 2012 did not meet the relevant criteria for acceptance.
The ACCC then consulted on a draft notice to vary in July on the detailed changes required to address the ACCC's concerns. The ACCC gave its final notice to vary to NBN Co in October 2013.
This process followed the submission and withdrawal of two previous undertakings dating back to December 2011.
Sims said it was a vastly different SAU than the version first submitted by NBN Co two years ago.
"Through the changes the ACCC requested and NBN Co has made, it is now a much more balanced instrument," he said.
The acceptance of the SAU by the ACCC provides the broad regulatory framework to facilitate effective engagement between NBN Co and access seekers to negotiate commercial agreements.
A spokesperson for the ACCC said it understood that a Wholesale Broadband Agreement (WBA) was currently under negotiation in the expectation of the SAU being accepted by the ACCC.
The ACCC recognises that there is some uncertainty around the NBN, especially in light of the upcoming reviews of the NBN, according to an ACCC statement.
"While this may have implications for the SAU, most of the commitments in the SAU are technology neutral and will apply even with a significant change in network design."
Sims said: "If, however, NBN Co wishes to vary the undertaking in the future in light of any new directions from the government, this can be accommodated," Sims said.
NBN Co may also withdraw the SAU at any time, by giving 12 months' notice.
The SAU and the ACCC's final decision are available on the ACCC website.