How is Australia's triple-0 emergency call network supposed to work?

In September, an Optus network outage stopped some customers from calling triple-0.

With four deaths linked to the outage, the incident has prompted serious discussions about the reliability of Australia's emergency services network.

Here's how it should be operating.

Who runs triple-0?

Australia's Emergency Call Service — usually referred to as triple-0 because the main phone number is simply 000 — is regulated and monitored by the Australian Communications and Media Authority (ACMA).

The ACMA is a federal government body.

How should calling triple-0 work from a mobile phone?

"Telco providers have a responsibility to make sure that when people make emergency calls to services like triple-0, that the call is connected," an AMCA spokesperson said.

"If a telco mobile network is una