The latest mobile service disruption is the fifth since 2011, and is the longest one by far, clocking over 40 hours as of yesterday.

September 2011

SingTel’s 3G services suffered three disruptions over two days, owing to a software glitch that occurred when the telco was installing new IP switches in the central region of Singapore to upgrade its network.

It affected about 25,000 SingTel subscribers for a total of 22 hours.

While the IDA ruled that the glitch was not SingTel’s fault, it said the telco had not been sufficiently diligent in determining the root cause of the glitch.

SingTel had continued to install new switches, even though it had not discovered the cause of the problem after the second service disruption.

The telco was fined a record S$400,000.

May 2011

A hardware fault left about 44,000 M1 subscribers unable to make and receive calls, send texts and use mobile data services for 12 hours.

Then, it was the first major mobile service outage since 1997.

The IDA’s investigation found that while M1 did not cause the incident, there was ‘undue delay’ by the telco in restoring services, as it did not have an effective contingency plan to resolve such problems.

The telco was fined S$300,000. It appealed the decision, but lost.