In a statement issued today the company said "between 15 December 2004 and 28 February 2005, all data downloaded between 2:00am and 8:00am will be unlimited and will not contribute to the customer's monthly data allowance".
The move to free up off-peak downloads was initially foreshadowed on broadband community user Web site Whirlpool.
The Unlimited and Unlimited Pro plans are designed for users with large download requirements.
The move comes after the company's release of a bundling plan whereby users can gain three or four months' broadband access each year if they take up an Optus product. The company has also eliminated the broadband installation fee if customers take up before the end of the year an Optus home phone for 12 months.
Whirlpool also reported that rapid transfer -- whereby customers can change ADSL providers quickly at minimal cost -- would be available on OptusNet ADSL from today.