Docomo suffers its second 5G SA outage in a week, disrupting calls and data in Japan

NTT Docomo, Japan's largest mobile operator, reported on Wednesday, November 11 an outage disrupting voice calls, data connections and SMS across the country, according to Yomiuri TV and the specialist publication Keitai Watch. The fault began at 10:34 Japan time, according to the company.

Docomo later specified that the problem affects customers of its 5G SA service, which runs on a dedicated 5G network without relying on the 4G network. According to Keitai Watch, the company says it does not affect other users, the virtual operators that use its network or emergency calls. Initial reports, carried by the Fukui Shimbun, spoke of a nationwide impact that also reached those virtual operators and said the effect on emergency calls was being checked.

According to Yomiuri TV, Docomo says the cause is "under investigation" but rules out unauthorized access or a cyberattack. The company recommends selecting the 4G network in the phone settings and restarting it or switching airplane mode on and off, and said it would announce later when it expects to restore service.

It is Docomo's second 5G SA outage in a week: according to Keitai Watch, the one on November 5 affected up to about 1.587 million people, according to the company itself. On its notices page, Docomo had published its sixth report on the 5G SA difficulties at 15:30 Japan time, without yet announcing that service had been restored.