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Optus

Every Optus engineering case study on TechLogStack — real production incidents, post-mortems, and fixes.

Optus Upgraded a Firewall and Accidentally Blocked Emergency 000 Calls for 13 Hours

A routine firewall upgrade on September 18, 2025, broke the routing path for Triple Zero emergency calls in four Australian states. Six hundred calls failed. Four people died.

13 hr outage window 600 failed emergency calls 4 states affected +1 4 confirmed deaths