Australian Prime Minister Julia Gillard will today switch on the first site of the National Broadband Network on mainland Australia.

Ms Gillard and Communications Minister Stephen Conroy will turn on the site at a secondary school in east Australian state of New South Wales.

It is one of five first-release test sites where fibre optic cable has been laid for the broadband network.

Areas in Melbourne, Townsville, coastal New South Wales and South Australia will also be switched on in coming months.

The principal of the Presbyterian Ladies College, where the launch will take place, says the students are excited.

Debra Kelliher says the National Broadband Network (NBN) will revolutionise the way students in regional areas learn.

"It could mean communication with other schools, and I'm also hoping it will give us a much greater global connection overseas," she said.

"We've done a bit of work with video conferencing but it's a bit limited by the equipment, so the NBN's connection is very speedy and fast and clear."

Head of product development at NBN Co, Jim Hassell, says the initial testing will start with just seven customers in New South Wales, which he says is not enough.

But he says that number will expand.

"Over our five first-release sites, we'll have about 1,000 customers," he said.

"We expect at Armidale that up to the end of September, that would be about 200.

"We will be increasing them on a weekly basis, taking on more and more people.

"Seven's not enough, but [they're] the first ones we've got and we'll increase that over the coming weeks."

Trial phases

Ms Gillard says NBN Co has deliberately picked very different sites.

"Armidale is one place it's going, but for example it's going to outer suburban Adelaide, so in a very different environment, an urban growth corridor," she said.

"They've done all of this deliberately to learn lessons for the rollout when it happens right around the nation."

Mr Conroy says it is a historic day.

"Regional and rural Australia have traditionally put up with very slow, very expensive and very inadequate telecommunication services," he said.

"That's changing from today and what we're demonstrating is the collaboration that is possible, the ability for people to gain access to the best quality education services."

But earlier this week NBN Co boss Mike Quigley said it was unlikely to meet some of its milestones for rolling out the NBN due to delays in finalising its deal with Telstra.

Telstra and NBN Co have signed a $11 billion agreement over infrastructure access and the future of the copper wire network, but it still needs to be approved by Telstra shareholders.

Mr Quigley told a parliamentary inquiry a final deal is likely to be several months away.