Optus has endured yet another outage, even as its embattled boss announced her departure after the telecommunications giant’s fraught 18 months.

As Kelly Bayer Rosmarin tendered her resignation on Monday, the company was also apologising to its customers in Melbourne’s west, where it had suffered an outage.

“Sorry, a number of Optus mobile towers in this area are not working,” the company wrote in an update to customers in Melton area.

“Our network team is working to resolve a cable break on the Optus mobile network in this area.

“Your mobile service may be interrupted during this time.”

Optus customers bore the brunt of another outage on Monday. Image: Twitter

Tweet from @Cee_Milly

Monday’s update followed the hours-long nationwide outage that affected millions of Australians a fortnight ago, and the 2022 Optus cyber attack when customer data was leaked to the dark web.

Bayer Rosmarin’s resignation came after she faced a Senate grilling on Friday – including denying reports she planned to quit the telco.

“It’s been an honour and privilege to lead the team at Optus and to serve our customers,” she said in a statement.

“I was also able to communicate Optus’ commitment to restore trust and continue to serve customers.

“Having now had time for some personal reflection, I have come to the decision that my resignation is in the best interest of Optus moving forward.”

Chief financial officer Michael Venter will assume the role of interim CEO while continuing in his current position.

Former Optus business managing director Peter Kaliaropoulos will become the company’s chief operating officer from Wednesday, a newly created position that will report to Venter.

Communications Minister Michelle Rowland wish Bayer Rosmarin well, and said resigning was “no doubt” a difficult decision.

“The Optus outage experienced earlier this month caused significant disruption to the community, particularly small businesses. We need to learn the lessons to ensure industry and government is as prepared as possible, given no network is fully immune,” Rowland said.

“The government has announced it will conduct a post-incident review and we will make further announcements about the terms of reference in due course.”

Bayer Rosmarin was appointed to Optus’s top job in April 2020, at the height of the pandemic. She was previously a high-level executive at the Commonwealth Bank.

In September 2022, Bayer Rosmarin presided over one of the telco’s worst PR disasters when it suffered a massive data breach that affected 10 million Australians and resulted in the licence, Medicare and passport numbers of 10,000 customers being stolen and leaked online.

A little over a year later, just as the company had begun to piece together the remains of its customers’ shattered confidence, Optus was hit by the 12-hour long outage that prevented more than one-third of Australians from accessing the internet and receiving cell service.

More than 200 emergency calls could not go through to the triple-zero line.

Yuen Kuan Moon, chief of Optus’s parent company Singtel, acknowledged the former CEO for her leadership, commitment and hard work during this “challenging” period and thanked Bayer Rosmarin for her dedication.

“Kelly has always led with integrity and had all stakeholders’ best interests at heart,” he said.

“We understand her decision and wish her the very best in her future endeavours.”

Following the November 8 outage, Bayer Rosmarin was summoned to a parliamentary inquiry where she was roasted by senators channelling the ire of their constituents.

During the Friday hearing, Nationals senator Ross Cadell queried her response during and after the network event and asked whether it was time for new leadership at the telco.

In response, she said she would “take that on board”.

-with AAP