NTT Docomo said on November 6 that a mobile service disruption affecting subscribers to its 5G SA (Standalone) service nationwide had been resolved at about 1:20 a.m. that day. The trouble began around 11:18 a.m. on November 5, leaving those users unable to easily make voice calls, use data or send SMS for roughly 14 hours.
Docomo traced the outage to congestion in the exchange that handles 5G SA subscribers. 5G SA is an option that connects only over 5G-dedicated equipment, which Docomo advertises as staying comfortable to use even when 4G networks are busy.
The carrier said its investigation so far, including the period around the start of the failure, has found no trace of unauthorized access and no event indicating a cyberattack.
Users outside the 5G SA subscriber base and MVNOs running on Docomo's network were not affected. Emergency calls were also unaffected.
The fix is complete, but Docomo is advising anyone still having trouble to restart their phone or toggle airplane mode on and off. It also asked users who switched their network settings to 4G as a temporary workaround to change them back.