Telstra’s finance chief Michael Ackland says police are still trying to contact 170 people who made failed triple-0 calls after it discovered a second network outage on Wednesday night, as the telco’s chief executive, Vicki Brady, flies back from a holiday to grapple with a deepening public relations crisis.

The country’s largest telecommunications company said 639 emergency calls failed to connect during the two outages, which disrupted public transport, payment systems and mobile services across the country.

“It’s unacceptable what has happened and our focus is on how we have addressed it through our processes, through the welfare calls and following up with customers as quickly as we can,” Mr Ackland said on Thursday lunchtime.

Mr Ackland said Telstra had handed 170 unresolved welfare checks to police, who were continuing efforts to reach those callers.

“We’re working through those welfare checks,” he said. “There’s still 170 that are with the police, and now, once we hand those to the police, it is for them to comment and update on anything,” he said.

Second outage, CEO flying back from holiday

Telstra chief executive Vicki Brady is flying back from a family holiday on Thursday and is expected to return to the office on Friday as the company faces mounting scrutiny over one of its most serious network failures in years.

The company also disclosed it had identified a second software failure on Wednesday night, extending triple-0 problems into Thursday morning after the initial nationwide network failure. It said it had implemented a fresh solution to the second software defect.

Initial investigations by the telco suggest software failed after a timer erroneously clicked back in servers in two Telstra-owned data centres in Melbourne and Sydney. Mr Ackland said comparisons to the Y2K bug where software programs were confused by clocks changing from the year 1999 to 2000 were off the mark.

“It’s not so much that it (the server software) clicked over and wasn’t able to deal with the format of the time, which was the concern during Y2K. It was a software glitch that caused the time to click back,” he said.

Mr Ackland also declined to comment on news reports linking the emergency call outage to a death in South Australia.

The telco’s finance chief also referred the public to a South Australia police statement that the force was not aware of any death associated with the outage.

Telstra informed the office of Communications Minister Anika Wells about the outage potentially impacting millions of Australians about two-and-a-half hours after first detecting an issue around 4.30am on Wednesday.

“So we always communicate with customers first when we see that there’s an issue, and there are certain thresholds in terms of when our obligations are to communicate with everyone. As soon as the incident reached that threshold, we communicated within minutes to the minister,” Mr Ackland said.

Victorian trains gradually return to normal service

Victorian train operator V/Line said rural services cancelled by the outage on Wednesday should return to normal from Thursday lunchtime, although it also warned travellers to expect delays.

The Ghan tourist train also left Adelaide on Thursday after being stranded overnight in the city due to the outage that also affected transport in Canberra and regional New South Wales.

The political theatre around the outage also extended on Thursday after Opposition Leader Angus Taylor defended his shadow communications minister Sarah Henderson from claims she acted foolishly by dialling triple-0 on Wednesday to test if the service worked.

“These actions were not illegal and were made necessary by complete and utter failure from the (communications) minister (Anika Wells),” Mr Taylor said on Thursday.

Minister Wells said the government department and telco had worked through Wednesday night and Thursday morning to seek assurance that all triple-0 calls were being connected and any missed were followed up on for welfare checks.

Telstra shares lifted 0.4 per cent to $4.94 on Thursday afternoon, versus a 0.4 per cent fall for the broader S&P/ASX 200 Index.

Mr Ackland also suggested it was too early to flag any specific compensation for personal or business customers affected by the outages.

“We’ll work through compensation as part of our BAU (business as usual) process and communicate with customers around that,” he said.

The company reiterated its apologies to the public on Thursday, but gave no guidance as to when the network will return to 100 per cent connectivity.

“We want to again apologise for the disruption these issues have caused to our customers and our community,” Mr Ackland said.

“We know how important it is to stay connected and we take this responsibility seriously.”

On Wednesday Minister Wells said the telco regulator the Australian Communications and Media Authority would conduct an investigation into the outage.