Telstra review says 2020 timing changes caused July outage

TL;DR: Telstra said an external review found its July outage was primarily caused by failures in network timing oversight, with Technology Audit Partners tracing the fault to 2020 changes that degraded the mobile core timing architecture and created a looping risk.

Telstra said an external review found that its July outage in Australia was primarily caused by the company not treating network timing as a critical network capability. CEO Vicki Brady said the outage resulted from insufficient oversight and protection of network timing.

Technology Audit Partners said modifications made in 2020 degraded Telstra's mobile core timing architecture and introduced the risk of looping, where network layers repeatedly confirmed the wrong time. The review said there was no evidence that the teams involved in the 2020 change were aware of or investigated that risk.

The outage affected Telstra's emergency call system. The review described the fault as the result of oversights and architecture decisions made over the previous six years.

The Light Reading report placed the incident in a wider pattern of telecom network failures. It cited an IEEE Access paper that referenced outages involving T-Mobile and Deutsche Telekom in 2020, KDDI and Rogers Communications in 2022, AT&T in 2024, and Telefónica in 2025.