We use the S.RIDE app to send text messages (SMS) from an international phone number to the numbers that customers have provided for the authentication of their mobile phones. Only phone numbers registered within Japan can be authenticated via text messages (SMS). You cannot use a phone with a phone number contracted outside of Japan.
Even when going through with authentication using a local Japanese phone number, please be aware that your phone may reject the receiving of text messages (SMS). As such, please check the below. (Settings differ for each carrier. After having checked your current setup, please allow your phone to receive text messages (SMS) from outside Japan until the initial setup is complete. Once the initial setup is complete, please put your phone back to its original settings.
For NTT Docomo: