"Our telecommunication provider continues to work to resolve their incident that is impacting our services", the CBA tweeted.
The CommBank app and NetBank are still working.
Westpac Banking Corporation said on Twitter that some automatic teller machines in Sydney were down, while National Australia Bank Ltd and Commonwealth Bank of Australia also reported payment processing issues.
"We're now looking into an issue affecting services including Eftpos and access to ATMs", the company said in a tweet at 4:19pm AEST on Thursday.
Telstra confirmed the issue in a brief statement.
The same issue hit St George Bank and Westpac.
CommBank is also advising not to call if you are now having issues.
- CommBank (@CommBank) July 11, 2019(2/2) We are experiencing higher than normal calls into our call centre.
"The cause of the problem is under urgent investigation and we are working to have full services restored as a matter of priority", CommBank said.
A Telstra outage has brought down Eftpos and ATM services around Australia, affecting Woolworths, the major banks and even McDonald's. "There is no need to call us if you are experiencing problems with these services".
Westpac said some branches, ATMs and services in Sydney were non-operational due to a broader network failure in the region.
'We're sorry if this impacts you.
"We know there are some issues with the following services: CBA ATMs, CBA EFTPOS terminals, some in branch services as well as issues logging onto the CommSec website".
The bank's ATMs are reportedly down in a number of locations around Australia, including in Sydney's CBD.
Some users are reporting problems making eftpos transactions, but it appears the issue is with the connections to merchant payment terminals. "Rest assured we are urgently looking into this and will have further updates soon", the company wrote on Twitter.
Caltex said its EFTPOS payments were being affected; Woolworths said electronic payments were being disrupted; while Australia Post said EFTPOS payments over $100 and other banking services were on the fritz, while withdrawals under $100 and all deposits were still working.
'Both of our eftpos machines have just gone down and your phone line goes straight to a message. Could I please get some answers?
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