The widespread outage affected the mobile network in Victoria, New South Wales and Queensland.
The telco earlier said technical teams were investigating the issue as a “priority and working to restore (it) ASAP”.
“We are aware that some Optus customers including residents and businesses may be experiencing intermittent disruptions to their mobile call, text and data services,” Optus posted on Twitter.
“We understand that connectivity is important and apologise for any inconvenience caused during this time.”
The outage caused chaos across shopping centres, with stores on the network reporting their payment terminals were down, as well as banks.
ANZ told a customer on Twitter the bank was experiencing “intermittent issues” with its payment terminal system.
“The team is trying to fix it ASAP,” the bank said.
“Please try processing the transaction using manual processing in the meantime or please seek alternate form of payment.”
Other customers vented they were unable to make or receive calls, send texts or use internet.
An Optus spokesperson told 9news.com.au customer services were restored this afternoon.