Internet service provider (ISP) Exetel has begun offering unmetered downloads between 1am and 9am for customers who are using services over the National Broadband Network (NBN).

"Exetel's new NBN plans are the first to market to offer true unmetered off-peak downloading between 1am and 9am, perfect for scheduling those large Windows, iOS, or Linux update downloads," the company said in a statement.

Exetel, which has 125,000 customers, announced its policy as part of an overhaul of its NBN plans that has also seen the price of its cheapest 12 megabit per second (Mbps) plan rise from AU$35 per month to AU$49.50 per month.

The biggest 100Mbps plan has had a boost in data up to 500GB from 300GB, but customers will have to pay for the privilege, with the AU$70/300GB plan gone and replaced with either an AU$94.50/250GB plan or an AU$139/500GB plan.

Customers wishing to sign up will also need to pay an AU$50 signup fee.

Exetel told ZDNet that the price rise for NBN products was due to an increase in the cost of backhaul for providing services on the NBN.

Exetel CEO Steve Waddington told ZDNet last month that it has around 5 percent of all users on the NBN.