Sydney, Sept. 19 -- Australia's second-largest telecommunications company has apologised after three customers died during a network outage that impacted hundreds of calls to emergency services on Thursday.

Optus, a wholly owned subsidiary of Singaporean conglomerate Singtel, on Friday confirmed that a network update on Thursday resulted in the failure of calls to Australia's national emergency telephone number, Triple Zero.

Optus Chief Executive Officer Stephen Rue said at a press conference in Sydney that approximately 600 customers in the states of Western Australia (WA), South Australia (SA), and the Northern Territory (NT) were affected.

"During the process of conducting welfare checks, three of the Triple Zero calls involved househ...