The WA government has confirmed the death of a 74-year-old man is one of three deaths linked to an Optus outage that left about 600 people unable to make triple-0 calls on Thursday.

The incident was made public during a snap media conference on Friday, with the telco blaming a technical fault identified in the process of a network upgrade.

It left people in South Australia, Western Australia and the Northern Territory unable to call triple-0, with SA Premier Peter Malinauskus saying the outage lasted for "over 10 hours".

On Friday night, South Australia Police said it had since identified the two deaths in its state, including that of an eight-week-old baby, that were acknowledged by Optus.

On Saturday morning, WA Health Infrastructure Minister John Carey confirmed the 74-year-old man'

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