An Optus customer has detailed the distressing moment she could not reach emergency services when her mother became trapped under her mobility scooter during the company's 13-hour outage.

Hundreds of calls to emergency services failed during the incident on Thursday in SA, WA, the Northern Territory and far west of New South Wales.

On Friday, Optus said three deaths were linked to the incident, including a 68-year-old woman in the Adelaide suburb of Queenstown, before another death in WA was revealed on Saturday.

On Sunday, SA Police said preliminary investigations indicated the death of a baby in South Australia was "unlikely" to have been caused by the Optus triple-0 failure.

Adelaide resident Kirsty McPherson, who is also a former triple-0 operator, told ABC Radio Adelaide on Monday

See Full Page