What is Disaster Emergency Message Dial?
Disaster Emergency Message Dial is a voice message board that is provided when a disaster such as an earthquake or volcanic eruption occurs, and is required when communication traffic to the disaster-stricken area increases and it is difficult to get through.
Please refer https://www.ntt-east.co.jp/en/saigai/voice171/index.html for more details
Instructions for using emergency dial service https://www.ntt-east.co.jp/en/saigai/voice171/images/manual.pdf