A nationwide Telstra outage has been resolved after it affected Eftpos machines and ATMs.

The outage, which began on Friday, affected a range of businesses on Saturday morning, including a number of taxi companies, a Telstra spokesman said.

"Our team worked through the night on the fix and we are seeing the machine-to-machine traffic returning to normal," the spokesman said in a statement just after 12.30pm on Saturday.

"All devices should now be capable of connecting."

During the outage people had been advised to carry cash instead of relying on tap-and-go payments.

"We sincerely apologise to customers for the impact it had through yesterday and overnight," the spokesman said.

The outage came days after an issue affected access to some Telstra apps and the company's website, including cloud services.