Last week, 10 million Optus customers woke to no phone or internet coverage. 

And then the problems dominoed from there.

Melbourne’s entire train network came to a screeching halt, and phone lines to hospitals were down. Some people were unable to call triple zero if they needed to.

For several hours, Optus’ CEO was also missing in action, and a two-line statement on the company’s website - that customers without internet couldn’t see - said Optus was “aware of an issue” and was working to restore services “as quickly as possible".

Today, technology editor David Swan on getting to the bottom of what caused the 16-hour Optus outage ahead of the CEO's expected appearance before a Senate inquiry this week.

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