Telstra CFO Michael Ackland has told media that the telco has not yet identified the root cause of Wednesday’s massive network outage, which affected mobile and data connectivity, payment systems and external regional rail networks in Victoria and New South Wales.

Telstra said that at approximately 4.30am (AEDT) this morning the telco identified an outage impacting some mobile voice calls and data services. “Most calls and data connections are now working correctly, and our teams are working urgently to restore the rest,” it said.

According to the firm, the issue affected a number of nodes that help keep time across its mobile network. “When these nodes are not operating as expected, other parts of the network can be affected, resulting in intermittent issues with some mobile calls and data services,” the telco noted. “We began investigating immediately and started work to restore services.”

“We know how much you rely on our network, and how much of a disruption this is to your day. For that we’re so sorry,” said Ackland. “Here’s what we know, what we’re doing, and what you can do in the meantime.”

“If you’re having trouble making a call, try again. The issue is intermittent and doesn’t affect every call or connection attempt, so a call that fails once may connect successfully on another attempt, depending on how it’s routed through the network,” said Telstra.

“If you have access to Wi-Fi at home or in the office, we encourage you to connect where possible. While you’re on Wi-Fi, services such as WhatsApp, FaceTime and Microsoft Teams will continue to work as normal,” said Telstra.

The telco said there was no reason to believe there had been any cyber security incident.