Major telecommunications companies provide disaster message board services that allow you to register and confirm safety information via the Internet.
Of these, NTT East and NTT West have started a "disaster message dial" service that allows you to register and confirm voice messages.
You can register a message by calling "171" from a landline or mobile phone and entering your own phone number.
To listen to the registered message, call "171" and enter the phone number of the person whose safety you want to confirm.
In addition, NTT DoCoMo, KDDI, which operates au, Softbank, and Rakuten Mobile provide a message board service for disasters that allows you to register and confirm safety information using your mobile phone number on the Internet.