Exclusive: Despite being signed up to a new alert system, the South Australian emergency service was not notified during September’s triple zero outage

• Follow our Australia news live blog for latest updates

• Get our breaking news email, free app or daily news podcast

South Australia’s ambulance service was signed up to a new system that is supposed to send notifications when Optus has a triple zero outage, but says it was not notified during the outage last month.

September’s triple zero outage was caused by a network firewall upgrade which blocked emergency calls for Optus customers in South Australia, Western Australia, the Northern Territory and parts of New South Wales.