Internet protocol phone connections between the eastern and western regions of Japan were disrupted for 3 1/2 hours Wednesday morning, the two regional telecommunications carriers of Nippon Telegraph and Telephone Corp. said.
Subscribers to NTT's Hikari Denwa Internet-based IP phone services via fiber-optic cable were unable to make phone calls between the two regions from around 6:30 a.m. to shortly past 10 a.m., NTT East Corp. and NTT West Corp. said.
The disruption was attributed to the failure of a control server connecting the eastern and western regions, they said.
Hikari Denwa subscribers number 1.7 million for NTT East and 1.47 million for NTT West.
The disruption followed the worst-ever breakdown of NTT East's Internet connection and phone services via fiber-optic cable May 15, hurting the reliability of the Hikari Denwa services.
The May 15 glitch disrupted Internet connections and phone services for up to seven hours in 14 eastern prefectures, affecting 2.39 million subscribers.