Optus says 228 calls to triple zero failed during a 12-hour outage that affected internet and phone services to millions of customers on 8 November. 

Kelly Bayer Rosmarin, the Optus CEO who resigned on Monday morning, had told a parliamentary inquiry on Friday that triple zero was supposed to redirect to other mobile networks if one of the major telcos crashed. 

“We absolutely believe the triple zero system should have worked and it’s critical for all Australians that the system can be relied upon,” she said.

She did not provide details on the nature of the emergency calls — whether it was to ambulance, fire or police services — but said Optus arranged welfare checks on all 228 callers once its network was working again.