Optus left 10 million Australians without service for 12 hours

On November 8, 2023, a routine network change at Optus cascaded into a nationwide outage that lasted about 12 hours. Roughly 10 million customers lost mobile and internet service, Melbourne's train network shut down, hospitals could not receive calls, and businesses lost electronic payments.

Optus's communication during the outage was criticised as vague and slow. CEO Kelly Bayer Rosmarin appeared at a senate inquiry the following week and struggled to explain the root cause in plain language. The outage came just over a year after a major data breach at the same company, compounding public anger.

Rosmarin resigned on November 20, 2023. Optus offered affected customers extra data as compensation and faced calls for stronger telecommunications regulation. The Australian government announced a review of network resilience.

The incident became a standard case study in how a single configuration error can paralyse critical infrastructure, and in how consecutive crises at one company can destroy executive credibility faster than either crisis alone.