The outage crippled the Optus network for almost 14 hours, causing more than 450 Triple Zero calls to fail. ‘Fundamental legal obligation’ACMA chair Nerida O'Loughlin said ensuring Australians can reach Triple Zero was a core public safety responsibility. "Australians rightly expect that when they call Triple Zero, their call will connect," O'Loughlin said. "Australians rightly expect to reach Triple Zero when they need it most, and telcos are legally obligated to ensure that connection occurs," Wells said. The case comes just weeks after another major telecommunications outage by Telstra disrupted payments, train services and blocked some Triple Zero calls.