[Important] Notice
Phone authentication (SMS/Voice) carries risks such as interception of verification codes and unauthorized call forwarding. Consequently, transitioning to more secure authentication methods has been highly recommended in recent years. Okta, the provider of the keio.jp authentication platform, also deprecates Phone (SMS/Voice) factors and recommends using alternatives like Passkey (Biometrics/PIN).
If you currently use Phone (SMS/Voice) as your primary Multi-Factor Authentication (MFA) method, please register and switch to "Passkey (Biometrics/PIN)" or "Okta Verify App" as soon as possible.
Although Phone (SMS/Voice) authentication is expected to remain available after June 1, 2026, as a backup option for situations such as device replacement or malfunction, its regular use will be deprecated to enhance security. (Please note that this method may be discontinued in the future.)
What Is SMS Authentication and Is It Secure?
https://www.okta.com/blog/identity-security/sms-authentication/
First-time registration of MFA (Multi-Factor Authentication)
To enhance security, please register your authentication factors for multi-factor authentication.
We strongly recommend registering two or more authentication methods in case of loss or malfunction.
First, register your phone number (recommended)
If you have a smartphone or mobile phone, please register your phone number as your primary authentication factor first.
As long as your phone number remains the same, it can still be used even after changing your device. Registering your phone number is the most reliable way to prevent login issues.
For phone authentication, you can choose between "SMS (Text Message)" or "Voice Call."
Note: Regarding Unavailable Phone Numbers or International Travel
Multiple phone numbers can be registered simultaneously.
International phone numbers are supported; however, depending on the SMS/Voice authentication system used by Okta, verification codes may not be delivered to numbers outside of Japan (+81).
If you do not receive the verification code within approximately 3 minutes, SMS or phone authentication may not be supported for that number.
If you do not have a phone number or cannot use your Japanese number while abroad, please refer to [STEP 2: Additional Setup(for Daily Use）] and register two or more authentication factors.
Alternative authentication factors:Passkey (Biometrics/PIN), Okta Verify App, TOTP, etc.