NBN Co external affairs general manager Trent Williams said it would take a decade to completely roll out the $38 billion network across Australia.

In its corporate plan, the company expects this to mean connections to 13 million premises by 2021.

But the company has not identified towns and cities to be connected to the network beyond last week's announcement on the project's first and second stages.

Tasmania was selected to trial the national fibre-optic network last year.

The NBN was officially launched in Armidale, New South Wales, last week.

Mr Williams defended criticisms of Tasmania's low uptake, and said the 600 live connections were ahead of company projections.

He said 2000 Tasmanian property owners had consented to have the network connected to their premises, most of which were waiting for existing telephone and internet contracts to expire before fully signing up to the NBN.

"The other point to remember is that it's early days yet - we're still in trial phase," Mr Williams said.

He denied that a rollout in metropolitan centres would have been a better sell for the network, rather than starting in Tasmania.

"The goal is to deliver high- speed broadband to the people that need it most and, let's face it, the bush has been neglected for a very long time," Mr Williams said.

Tasmanian NBN users have told The Sunday Examiner that communication with internet users with a lower digital bandwidth was much slower than the one-gigabyte-a-second promised.

One Smithton business owner, Brett Dawes, said from his six months' experience, internet users must be on the same bandwidth for the network to work properly.

"There is not much point having a patch connected here and a patch connected there - it's all or nothing," he said.

But Mr Williams denied all internet users needed to be on the same bandwidth for the full potential of the NBN to be realised.

"When we talk to the schools and small businesses that are already using the network in Tasmania, it's made major differences to how they educate kids and how they run their businesses," he said.

"Obviously we see these benefits continuing to be amplified as more and more people are connected to the network, but improved experience and opportunity is a reality already."