by KDDI, the second largest telecommunications company in Japan, suddenly crashed its VoLTE voice system in the early morning of July 2. 30 million users could not make calls or surf the Internet for more than two and a half days. Even the Meteorological Agency urgently announced that Typhoon Elilai Full weather information was not available during the storm. Thousands of calls to report the case could not be made. Not only did climbers on remote mountains get injured and could not report their injuries, they almost endangered their lives. More than 5 hospitals were unable to contact surgeons, and no one could help critically ill patients perform emergency operations. The sudden nationwide crash in Japan not only disrupted the pace of life of many people, but also greatly affected the operations of many companies. Many services that depended on the Internet were interrupted, and it also caused system failures. This communication crash is not only the most serious communication failure accident in the 22 years since KDDI was established, but also the largest telecom service interruption accident in Japanese history.
