Japan's Largest Telecom NTT Faces Outage... Emergency Calls Also Down

A connectivity outage occurred in some communication networks of NTT Group, Japan's largest telecommunications company, causing telephone and internet services to go down in the metropolitan area and Osaka region on the morning of the 3rd.

According to major Japanese media such as NHK, around 7:10 a.m. that day, some internet services and the wired internet phone service called 'Hikari Denwa' were disconnected in the Tokyo metropolitan area including Tokyo and Kanagawa Prefecture using NTT East Japan lines, as well as in the northernmost Hokkaido region. In the affected areas, emergency calls to police and fire departments also failed to connect.

NTT Docomo

Jiji Press reported that due to the service outage, about 359,000 internet subscribers and approximately 186,000 customers using Hikari Denwa in the East Japan region were unable to make calls for three hours. SoftBank, which uses NTT's optical fiber lines, also experienced disruptions in internet services due to this incident.

At the same time, communication failures occurred in areas including Osaka Prefecture, Shiga Prefecture, and Gifu Prefecture using NTT West Japan lines.

NTT East Japan restored services at 10:08 a.m., about three hours after the outage began, while NTT West Japan restored services at 8:49 a.m., about one hour and 30 minutes after the outage started.

The communication failure is reported to have been caused by equipment malfunction, and NTT is currently investigating the exact cause of the incident and any additional affected areas.

Previously, in July last year, a large-scale network outage occurred in the communication network of KDDI, one of the three major mobile carriers in Japan. KDDI's communication services were suspended for two days, causing disruptions in weather data transmission, transportation, and financial services. KDDI estimated that 39.15 million subscribers were affected by the outage and decided to pay a total compensation amount of 7.3 billion yen (approximately 713 million KRW), including refunds.

This content was produced with the assistance of AI translation services.