The support systems are valued at hundreds of millions of dollars, adding to the almost $2 billion and 60 tenders in contracts already accounted for by NBN Co so far. Brown conceded that the systems were not designed to last the life of the NBN, but that the company was buying in high volumes to keep costs down in the short term.

"Our final support maintenance model is also what we're working through at the moment, which is where the tail of the cost comes from," he said.

"We're trying to get the trifecta here - integrated so it works, which most multi-domain software packages struggle with despite the promise. Get it so that it enables our partners to interface with us easily and cheaply, and to operate it and maintain it cheaply.

"We are absolutely keen to achieve all of those three objectives and I'd have to say at the moment, we think we can get there."

NBN Co chief executive, Mike Quigley, following the Federal election in August last year. While Quigley said he "would have loved" to implement an existing OSS/BSS (business support system) for the network, the final NBN systems would have to be tailored specifically to the unique network.