A major system failure last week affecting Japan’s largest mobile carrier NTT Docomo Inc. constitutes a “serious incident” under the telecommunications law, according to Japan’s communications ministry.
The ministry is considering issuing an administrative order, ministry officials said Tuesday.
NTT Docomo will be asked to report to the ministry by Nov. 13 the causes of the outage as well as its measures to avoid such incidents from occurring in the future, the officials said.
According to the law on telecommunications business, for a call service that handle emergency calls, a malfunction that affects more than 30,000 people for more than an hour is considered a serious incident.
The communication failure occurring around 5 p.m. Thursday local time during work on NTT’s network made about 2 million users completely unable to use call and internet services for more than two hours before the system was fully restored at 10 p.m. Friday local time.
The company said earlier its system responded in an unexpected way during the work on Thursday, and when it tried to restore services, the data backing up during the outage overwhelmed the system.
In January 2019, the Ministry of Internal Affairs and Communications instructed Japan’s third-largest carrier SoftBank to improve its response after a software failure caused by Telefonaktiebolaget LM Ericsson, when more than 30 million user accounts were affected for more than four hours.
