The Senate hearing into the Optus network outage on November 8 was a reminder of the oldest business lessons in the book: it’s not the mistake you make, but how you handle the clean-up.

On Friday, Optus chief executive Kelly Bayer Rosmarin gave the clearest explanation we’ve heard so far about the cause of the outage: a sudden and unexpected shutdown of 90 routers across Optus’ mobile and data networks, which was triggered by upgrades to an international peer network operated by Optus’ parent company, Singapore Telecommunications.