Telstra has confirmed the resignation of its chief information security officer (CISO) Mike Burgess, saying he will depart the company on November 4.
"After three years with Telstra as CISO, Mike Burgess has decided to explore new opportunities," a Telstra spokesperson said in a statement.
"During his time at Telstra, Mike established proven and effective security capabilities that play a critical role in keeping our customers' data safe and our networks secure.
"Mike is leaving Telstra with the right strategy and capabilities developed and implemented -- and as a company, we will continue to build on these. We wish Mike every success in the years to come."
Telstra added that it will be searching internationally for a new CISO.
Burgess' resignation follows the resignation of Telstra CIO Erez Yarkoni in August and the retirement of COO Kate McKenzie in July, as well as the departure of CTO Vish Nandlall amid reports of CV fraud in May.
Telstra last week apologised at its AGM for letting down its customers and shareholders through the network outages throughout the first half of calendar 2016, revealing it dropped four points off its Net Promoter Score (NPS) customer experience measurement over the same period.
According to Telstra chair John Mullen, there is "nothing inherently wrong" with the telco's networks, with the strain caused by a dramatic rise in traffic partially responsible for the seven outages between February and June.
The first outage occurred on February 22, affecting prepaid and post-paid mobile services, and was caused by "embarrassing human error"; the second was on March 17, which involved an hours-long national mobile data and voice outage; and the third was on March 22, which was a smaller voice outage.
Telstra then experienced an NBN and ADSL outage in May that resulted in the telco having to send free modems to customers still affected several days later; a mobile data services outage later that week; a broadband service outage in June; and an outage that took down businesses across Victoria, including banks, hospitals, department stores, and airline Jetstar.
As a result, Telstra CEO Andrew Penn in June committed the telco to investing an additional AU$250 million in its network over the next six to 12 months in three major areas: AU$50 million to be spent on improving mobile network resiliency by creating better real-time monitoring and speeding up recovery time; AU$100 million on increasing the core fixed-line network's reliability and resiliency; and AU$100 million on upping its ADSL broadband capacity to cope with demand.