More than 10 million Optus customers and businesses were thrown into disarray on Wednesday after the telco's network dropped out about 4am, preventing people from connecting to the internet or making or receiving calls.
It took more than 12 hours before services were eventually restored.
There are calls for the company to explain why the nation's second-most popular telecommunications network went down.
The Greens are pushing for a federal parliamentary inquiry in the Senate to examine what led to a nationwide outage of the Optus network.
"We need to make sure that all Australians have access to affordable and reliable internet and telecommunication, because otherwise, life as we know it stops, and that's what Australians right around the country experienced (yesterday) morning," Greens Senator Sarah Hanson-Young said.
Businesses have been dealt multiple blows, a day after the Reserve Bank increased interest rates, National Retail Association director Rob Godwin said.
"This is costing businesses thousands of dollars in sales that they are now in dire need of given yesterday's rate hike," he said.
Optus chief executive Kelly Bayer Rosmarin said she understood how much people rely on the connectivity and that the company will now consider ways to compensate them for the trouble caused.
'We're now starting to think about ways in which we can thank our customers for their patience as we work through the outage today and reward them for their loyalty to Optus," she told ABC News.
"We will definitely consider every avenue as we turn our attention, now that services are restored, to how we work with our customers."
Close to 10 million Optus customers had their personal information stolen when the company's data system was breached last year.Â
But the telco believes a network fault was behind the outage, as investigations continue into the root cause.
People weren't able to make calls to triple zero on Optus landline devices during the outage, although it was still possible to do so on a mobile phone.
Public infrastructure including Melbourne's metropolitan train network ground to a halt early on Wednesday before slowly resuming with major delays throughout the morning peak.
Service NSW call centres, Victoria's virtual emergency department and Northern Health hospital phone lines were also down during the Optus outage.
