By Kimberley Kao


Singtel's Australian subsidiary Optus suffered another network outage, the latest in a series of disruptions that have cast a cloud over the Singapore company.

Optus, one of Australia's largest telecom companies, faced a new outage over the weekend that disrupted emergency calls, sending shares in Singtel down as much as 3.8% early Monday. Services have since been restored.

Optus said in an update Monday that it is continuing to investigate the cause of the issue involving a mobile phone tower site in the Dapto area of New South Wales. The problem affected around 4,500 people and calls made between 3 a.m. and 12:20 p.m. on Sunday, including some emergency calls.

Optus apologized to affected customers and said it "confirmed with police, all callers who attempted to contact emergency services are OK."

The disruption came just over a week after a similar network outage led to the deaths of four people who couldn't reach emergency services in time.

At a press conference Monday, Australian Treasurer Jim Chalmers said the government has asked the Australian Communications and Media Authority to investigate.

"This can't happen again," Chalmers said. "This is an absolutely shocking failure from Optus."

Optus contributes about half of Singtel's operating revenue. Singapore's largest telecom operator has said that it has supported Optus by investing more than 9.3 billion Australian dollars, equivalent to $6.09 billion, in the past five years, with a large part of the spending going toward building network infrastructure across Australia.


Write to Kimberley Kao at kimberley.kao@wsj.com


(END) Dow Jones Newswires

09-29-25 0147ET