Auth0 Support Center - SMS Send Failures for an MFA Integration with Twilio

SMS Send Failures for an MFA Integration with Twilio

Multi-factor AuthenticationEmail, Voice, SMS Integrations

Sep 10, 2025

Overview

This article explains the cause of the SMS send failures for MFA setup using Twilio.

Sample error log:

{
"type": "gd_send_sms_failure",
"description": "Guardian - There was an error sending the SMS",
..redacted
"details": {
    "failure_details": {
      "errorCode": "sms_provider_configuration_delivery_error",
      "message": "Provider reported delivery error"
    },
    "provider_error": {
      "errorCode": 20003,
      "message": "Authenticate"
    }
    ..redacted
}
}

Applies To

Twilio
SMS Error
MFA Integration

Solution

The provider_error section in the details field of the gd_send_sms_failure logs shows the errors Auth0 receives from the SMS service providers.

In this case, 20003 is an error code from Twilio. They have this documentation explaining the potential causes of the error.