(SOURCE: TAKATOSHI KURIKAWA/ALAMY STOCK PHOTO)

Asia's network outage contagion has spread to NTT Docomo, with the Japanese telco experiencing two lengthy disruptions on its 5G SA network in five days.

In both cases the multi-hour outages were caused by congestion In the switching equipment that supports 5G SA services, Docomo disclosed. The company has not yet given any indication of the underlying cause of the congestion problem.

In the first disruption last Friday, voice, messaging and data services were unstable or unavailable for nearly 14 hours. The incident affected 1.5 million customers who had signed up separately for the 5G SA service. It did not affect other 5G or 4G users, or MVNO customers.

In the second event, the same services on the 5G SA network were disrupted for around nine hours on Wednesday. NTT Docomo said investigations had found no evidence of unauthorized access or cyberattack.

It seems most likely a software fault related to the switching kit was to blame, but the company is still probing the issue. Based on past disclosures, the equipment was likely supplied by Ericsson.

Singtel fine

The Japanese firm is not alone among Asia-Pacific telcos in experiencing network crashes recently. Last month, Singtel was fined 1 million Singapore dollars (US$778,000) for a series of outages that affected 600,000 customers in March.

The fault was the failure of a chiller system that forced network equipment to overheat and shut down, creating traffic congestion for the next two days.

Australian operators Telstra and Optus have experienced major outages over the past 18 months that have taken down the national emergency call network on multiple occasions, prompting widespread anger and calls to take the emergency system out of their hands.

Besides the network faults, NTT Docomo's online store has been hit by a cyberattack that exposed the private data of 300,000 customers.

CEO Yoshiaki Maeda last Friday apologized for the breach as well as for the network disruption. He said the company is still investigating the incident and is considering paying compensation to affected customers.