Under-fire telco Optus has announced an independent inquiry into how technical failures left people unable to access triple-zero services. Kerry Schott will lead the external review into last week's catastrophic outage linked to up to four deaths, as a potential axing looms for chief executive Stephen Rue. Dr Schott's review will press for the causes of the outage and examine the operational management of triple-zero calls on the Optus network. A potential axing looms for Optus chief executive Stephen Rue. (Dave Hunt/AAP PHOTOS)This comes as another telco has revealed it has changed its emergency call handling and technology after Optus' 2023 outage.