KDDI Corp.’s mobile phone and data communications services are disrupted across Japan on Saturday, the major Japanese telecommunications carrier said. 

The problem started at around 1:35 a.m. (4:35 p.m. Friday GMT), and when it can be resolved remains uncertain, according to the company.

The company said that a glitch happened telephone exchange equipment after midnight, causing network congestion. The company restricted data flows in order to reduce the load on the network, resulting in the service disruption.

The communications ministry instructed the company to get its services up and running again as soon as possible.

“We deeply apologize for causing much inconvenience,” KDDI said in a statement.

The disruption is affecting not only KDDI’s “au”-, “UQ”- and “povo”-brand mobile services but also services of Rakuten Mobile Inc. and low-cost carriers using KDDI’s network.

KDDI has about 62 million contracts for its services, around 31 million of which are with individual subscribers to the mobile services under the three brands.

Among businesses affected by the KDDI problem, Yamato Transport Co. was unable to update parcel delivery status on its website while its delivery-truck and call center operations were disrupted.

According to Japan Airlines KDDI transceivers for its staff at Narita International Airport in Chiba Prefecture, east of Tokyo, and Tokyo International Airport at Haneda became unavailable, but there have been no implications for its flight operations as devices using a different company’s network are used instead.

Ogaki Kyoritsu Bank based in the central prefecture of Gifu, said some of its automated teller machines were unavailable.

Meanwhile, the Japan Meteorological Agency experienced some difficulties in transmitting data of its Automated Meteorological Data Acquisition System.

The KDDI disruption came after rival carrier NTT Docomo Inc. caused a large-scale disruption in its phone and data communications services in October last year, leaving around one million users unable to use the services for two hours and 20 minutes.

Finding that the incident affected a total of some 12.9 million people, including those who experienced inconvenience from mobile traffic congestion, the communications ministry issued an administrative guidance to NTT Docomo.

At the time, other service providers including KDDI also conducted emergency inspections to prevent disruptions.

Under Japan’s telecommunications business law, any disruption making it unable to make emergency calls for at least an hour and affecting more than 30,000 people is required to be reported as a “serious incident” to the ministry.

JIJI Press