Summary

  • The ACMA's concluded investigation into the 8 November 2023 outage found 2,145 occasions on which Optus failed to give end-users access to the emergency call service, apportioned across three named entities: Optus Mobile Pty Limited (2,091), Optus Networks Pty Limited (41) and Optus Internet Pty Ltd (12). Required welfare checks were not undertaken on 369 occasions.
  • Optus's public figures moved from 228 failed calls to 229, then to at least 2,697. Failed calls, unanswered unique service numbers and welfare checks are different measures; the record supports several attributed numbers, not one settled count.
  • The 2023 matter closed in more than $12 million of ACMA infringement notices — administrative, not a court finding. The Federal Court proceedings commenced on 30 July 2026 concern the separate 18 September 2025 outage, name Optus Mobile Pty Limited, allege 1,005 contraventions, and remain pending.
  • The unresolved question is control: which entity held the emergency-call path, the change controls and the welfare-check duty — and whether independent evidence shows the repair was tested rather than assured.

A twelve-hour failure, counted afterwards

Services were lost across Australia from about 4am AEDT on 8 November 2023 and largely restored by about 4pm AEDT. The ACMA opened its investigation on 13 November 2023 and later found that Optus Mobile failed to give 2,091 end-users access to the emergency call service, Optus Networks 41, and Optus Internet Pty Ltd 12 — 2,145 failed emergency calls in total — and that required welfare checks were not carried out on 369 occasions (Optus Mobile 361, Optus Networks 8). The regulator rejected Optus's contention that section 15 of the Telecommunications (Emergency Call Service) Determination 2019 concerned only network configuration rather than establishing and maintaining actual calls (ACMA investigation report).

The number moved, and only upwards

Optus told the Senate committee's public hearing on 17 November 2023 that 228 calls failed to connect to Triple Zero, revised that to 229 on 24 November 2023, and advised of an additional 2,468 unique service numbers whose calls to the emergency call person were not answered; it said it had undertaken 228 welfare checks and confirmed the callers were “okay” (Senate committee report, chapter 3). On 23 January 2024 it advised the committee that the 229 figure was not accurate and that the number was at least 2,697 (Senate committee report, chapter 2).

Those figures are not interchangeable. Failed calls, unique service numbers whose calls went unanswered, and welfare checks not performed count different things, and the regulator's finding of 2,145 refers to the first measure. The documents reviewed for this briefing do not reconcile the operator's later “at least 2,697” with the regulator's 2,145, and the three apportioned entity counts sum to 2,144 against the stated total of 2,145; that residual is likewise not explained there. News coverage at the time of the penalty recorded the welfare-check failures as more than 300 (ABC News, 8 November 2024).

Twelve calls, and the entity boundary this briefing follows

Optus Internet Pty Ltd, the entity this briefing follows (directory entry), carries the smallest attributed share: 12 of the 2,145 failed emergency calls, and none of the 369 welfare-check failures. The number is small; the boundary it draws is not. The regulator assigned counts to named legal entities rather than to the Optus brand, which makes each named company's exposure and role separately legible — and separately checkable.

What the concluded record does not set out is the attribution method — how a failed call was assigned to one entity rather than another — or the control boundary: which entity held change management over the core network, emergency-call-path redundancy, post-incident integrity testing and the welfare-check duty. Those are the questions that have to be answered before anyone can say the failure was repaired rather than counted.

An administrative ending for 2023, a court case for 2025

The 2023 matter closed with more than $12 million in penalties paid by subsidiaries of Singtel Optus Pty Limited; ACMA Chair Nerida O'Loughlin said the size of the penalty reflected the critical nature of the breaches (ACMA, 8 November 2024). The outcome was an infringement-notice penalty — administrative, not a court judgment — and the ACMA's later statement describes the same rules as the ones Optus “was penalised $12 million by the ACMA” for breaching in 2023 (ACMA statement).

On 30 July 2026 the ACMA commenced proceedings in the Federal Court against Optus Mobile Pty Limited over the 18 September 2025 outage, alleging breaches of two legal obligations on 1,005 occasions; the maximum penalty available to the court is $250,000 per contravention (ACMA, 30 July 2026). News reporting describes the two alleged breaches for each failed call — not giving access, and not carrying the call to the relevant termination point (WAtoday, 30 July 2026) — and records the ACMA's stated concern that a major outage affecting emergency calls recurred so soon after November 2023, and that the earlier action ended in more than $12 million of infringement notices (ABC News, 30 July 2026). Optus told the Singapore Exchange it is reviewing the pleadings, will respond in due course, and cannot determine penalty quantum, which would be a matter for the Federal Court (Optus disclosure, 30 July 2026).

These are allegations. No court has made findings in the 2025 matter; the 2023 findings are the regulator's concluded findings; and the only entity named in the pending case is Optus Mobile Pty Limited.

What the record cannot yet answer

Whether the failure was repaired — and who can prove it. The reviewed record contains no independent test, audit or assurance result showing that the emergency-call path was verified after November 2023. It contains a second outage affecting emergency connectivity in September 2025, a pending proceeding that invokes the same rules, and the operator's assurance, which is not the same as evidence. That gap, not the size of the count, is the durable question for the entity this briefing follows, and for every operator whose continuity obligations rest on the same rulebook.