The telco said in a message on its Facebook page at 6.49pm AEST that most services had returned and it was working on the remaining few that were still offline, along with its business partners.
The outage affected the big four banks — NAB, ANZ, Commonwealth and Westpac — as well as the Bendigo and Adelaide Bank.
Additionally, big retailers like Woolworths, Australia Post, Coles and Caltex were all unable to accept payments by card.
"There are issues with the following services: CBA ATMs, CBA EFTPOS terminals, some in branch services as well as issues logging onto CommSec."
Later, at 9pm, the bank said: "Services have returned to normal including our ATMs. We apologise and thank you for your patience today as we worked to restore services."
? Most services are now back online and we’re working with our enterprise partners on the remaining few. We're continuing to keep an eye on all services as this happens. Thanks for your patience.— Telstra (@Telstra) July 11, 2019