Telstra has blamed a software fault for its widespread network outage on Monday, which left customers unable to make calls or use mobile data.
The telecommunications giant said a software fault triggered multiple elements across its 4G network to fail, and a further fault caused an interruption on the standby hardware, which resulted in customers dropping back to the 3G network.
Telstra said it took about two hours to restore full service, and it is still investigating the root cause of the software fault.
A May 4 lightning strike had previously shut down the national emergency phone network.
Telstra also had another outage on May 1, when customers were unable to make or receive calls for several hours.
Monday’s crash had brought a furious reaction on social media and apologies from Telstra.