The ISP, one of Australia's largest with around 85,000 customers on broadband and another 60,000 on dialup Internet, has already linked its Western Australian network up with Optus'.
While a Westnet spokesperson had not supplied details of any change by time of publication, a network engineer at the ISP had recently revealed its plans to switch to the Singapore Telecommunications-owned unit.
"No secrets here, we have changed our upstream providers as happens from time to time," Chris Atkinson wrote on the forums of broadband information site Whirlpool.
Atkinson said Westnet was currently using Telstra as its upstream Internet provider in Tasmania and the Australian Capital Territory, with AAPT holding the ISP's business in the other states and the Northern Territory.
"You'll be happy to hear that in the near future all states will be following WA and moving onto the Optus network," he wrote in a later post.
However, Atkinson didn't specify a firm timeframe for the Optus links to be switched on.
"As soon as the services can be delivered by the chosen supplier we will turn them on, within reason and after a suitable period of testing and of course taking into consideration things like contracts etc," he wrote.
In related news, Westnet is understood to still be testing network hardware as the ISP decides whether it will follow larger companies like Telstra, Optus and iiNet and roll out its own ADSL infrastructure into telephone exchanges.