invalid-app-credential/Invalid token. Error on phone auth

[KEI SHIBATA]

Hi,

I have a iOS Flutter app using Firebase phone auth.

when I call verifyPhoneNumber() ,I'm getting error and SMS not received.

The error message says "Invalid token." .

I have no idea about the token, Is this a FCM token or Apns token ??

Is there anyone knows the token means.

Any advice and / or suggestion is appreciated. 

Regards,

KEI