Japan's NTT Docomo Apologizes After Second 5G SA Network Outage in Five Days

NTT Docomo has issued an apology after suffering its second nationwide network disruption in less than a week, with the latest incident leaving users of its 5G Standalone service without voice, data, and SMS connectivity for approximately nine hours.

The most recent outage began at 10:34 a.m. local time on November 11 and was not fully resolved until 7:17 p.m., according to the carrier. The disruption affected customers on 5G SA contracts, who experienced difficulties making voice calls, accessing data services, and sending SMS messages. Standard 5G and 4G services remained operational, and emergency calls were unaffected. Mobile virtual network operators relying on Docomo's network were also not impacted.

The incident follows a far longer disruption last Friday, which persisted for 14 hours and affected approximately 1.5 million customers on the same 5G SA platform. Together, the twin outages represent a significant operational challenge for Japan's largest mobile carrier as it continues to roll out advanced 5G capabilities nationwide.

In a statement addressing the November 11 disruption, NTT Docomo attributed the failure to congestion in the exchange equipment serving 5G SA subscribers. The company said its investigation had "not revealed any signs of unauthorized access or cyberattacks, including before or after the incident." Docomo did not disclose vendor details related to the affected infrastructure, though Ericsson announced earlier this year that it would supply the carrier with its radio access network compute platform, including for 5G Advanced networks.

The back-to-back outages compound a difficult year for NTT Docomo on the security and reliability front. Earlier in 2026, the carrier suffered a significant cyberattack that compromised data belonging to approximately 300,000 customers. The recurrence of service disruptions within such a short window is likely to intensify scrutiny of the carrier's network resilience and incident response procedures, particularly as Japanese consumers and enterprises grow increasingly dependent on 5G SA for mission-critical applications. For the broader telecom industry, the events underscore the operational risks inherent in transitioning to standalone 5G architectures, where signaling congestion and equipment capacity constraints can cascade into widespread service failures if not adequately managed.