Optus went dark for 14 hours, cutting off 10 million Australians from everything

On November 8, 2023, Australia's second-largest telecommunications company suffered a total network failure that lasted 12 to 14 hours, affecting more than 10 million individuals and 400,000 businesses. The outage took down mobile phones, home internet, landlines, EFTPOS terminals, hospital switchboards, and the Triple Zero emergency call service across the country.

The cause was a Border Gateway Protocol (BGP) routing failure triggered by a software upgrade at a Singtel North American exchange. When one router disconnected as a protective measure against routing update overload, approximately 90 edge provider routers followed, setting off a cascading shutdown that the network's automated safeguards could not stop. The outage lasted from 4:05 AM AEDT until late afternoon, with some services recovering only the next day.

The financial damage was severe. Singtel, the Singaporean parent company, lost over AU$2 billion in market value as its share price dropped 4.8% on the Singapore Exchange. Optus CEO Kelly Bayer Rosmarin faced intense criticism for the company's slow and vague communication during the crisis. She resigned a week later, and the company offered affected customers 200 GB of bonus data as compensation.

The Australian government commissioned an independent review led by Dr. Richard Bean, which released 18 recommendations. The Senate also held a public inquiry. The review called for new customer communication rules, a Triple Zero testing regime, and the creation of a dedicated Triple Zero custodian to prevent a recurrence.