M1 said it will appoint an independent expert to review its network architecture and connectivity in the aftermath of the service disruption on February 4.The telco said investigations into the service breakdown are still ongoing, even as it assured customers that it has taken "immediate measures" to enhance its network.
M1 said the disruption that left its customers unable to make calls or send SMSes for more than five hours was caused by a call processing software issue.
"This issue originated from a pair of mobile site switches which performed in an unstable manner, causing intermittent connection problems between our switches and customer databases," M1 said on Monday, as it released its preliminary findings.
"To make voice calls, customers have to be authenticated by our network. This is the beginning of the call processing flow.
"However, the intermittent connection interrupted the authentication process.
"These unsuccessful authentication attempts tied up network resources, leading to congestion at the customer databases.
"The congestion cascaded to another network layer, tying up additional network resources and preventing customers from making or receiving calls,” it added.
M1 said it is continually upgrading its network to deliver better customer experience and improve network resiliency.
The telco’s chief executive officer Karen Kooi said that M1’s more sophisticated network has inevitably increased the level of complexity in troubleshooting.
She said that “while the root cause for the mobile site switch instability is being investigated, we are reconfiguring our site switches to eliminate congestion that may arise due to unstable intermittent connections.”
She added that M1 will also be deploying a software enhancement that will enable the telco to better manage sudden and unexpected extreme traffic conditions.