Congestion on the national broadband network has eased as more customers turn to higher speed plans after rollout company NBN Co slashed its top speed packages last year.

The company, which has more than doubled its first-half revenue thanks to a surge in new connections to the network, says it is working to improve its service following a spike in complaints last year.

In December, NBN Co gave retail service providers a temporary discounted wholesale price for its higher speed packages in a bid to boost top-tier use and respond to concerns expressed about its data charges.

It also paused all activations on the hybrid-fibre coaxial (HFC) network in November in order to conduct upgrades and improve the quality of service.

On Monday, the company said it is already seeing less congestion in peak-hour usage times and greater demand for its wholesale higher speed plans.

Chief executive Bill Morrow said that before the December promotion there were 140,000 customers on NBN's 50Mbps plan - its second highest speed package - but since implementing the temporary discount about 207,000 have signed on to the faster plan.

He expects that number to grow to more than a million by the end of the fiscal year.

"Before our announcement, only three per cent of new orders were for the 50 Mbps plans, they now make up 30 per cent of orders," he said.

"We wanted retail providers to offer the benefits to end users quickly and this is already having a profound impact.

"All signs show that the new wholesale pricing is working well and the more services we get on the higher speed products the better."

Previously, there were on average seven hours in a week per customer that would be congested - particularly in the evening and towards the end of the week, Mr Morrow said.

"Now, with the change, we have seen from six or seven hours average a week to less than 30 minutes and that is before all of the migrations we are currently processing."

The Australian Competition and Consumer Commission found, in a report released last week, that there had been a 38 per cent jump in the amount of capacity bought by retail service providers such as Telstra and Optus last quarter.

NBN Co's revenue for the six months to December 31 rose to $891 million, from $403 million a year ago, with more than 940,000 new homes and businesses signing up to the network - resulting in almost 3.4 million premises now on the network.

The company said that by December 31, 6.1 million homes and business were ready to order a service from their preferred retailer, up from 3.7 million at the same time a year ago.

Mr Morrow said that more than 95 per cent of households and businesses were in a design or construction phase or were already able to order a service over the NBN.

"While that is success we can be proud of, we've demonstrated that we won't pursue those objectives single-mindedly at the expense of customer experience."