Some API operations in a user pool generate a challenge, like a prompt for an MFA code, for device authentication that bypasses MFA, or for a custom authentication challenge. A
RespondToAuthChallenge API request provides the answer to that challenge, like a code or a secure remote password (SRP). The parameters of a response to an authentication challenge vary with the type of challenge.
For more information about custom authentication challenges, see
Custom authentication challenge Lambda triggers.
Amazon Cognito doesn't evaluate Identity and Access Management (IAM) policies in requests for this API operation. For this operation, you can't use IAM credentials to authorize requests, and you can't grant IAM permissions in policies. For more information about authorization models in Amazon Cognito, see
Using the Amazon Cognito user pools API and user pool endpoints.
This action might generate an SMS text message. Starting June 1, 2021, US telecom carriers require you to register an origination phone number before you can send SMS messages to US phone numbers. If you use SMS text messages in Amazon Cognito, you must register a phone number with
Amazon Pinpoint. Amazon Cognito uses the registered number automatically. Otherwise, Amazon Cognito users who must receive SMS messages might not be able to sign up, activate their accounts, or sign in.
If you have never used SMS text messages with Amazon Cognito or any other Amazon Web Servicesservice, Amazon Simple Notification Service might place your account in the SMS sandbox. In
sandbox mode, you can send messages only to verified phone numbers. After you test your app while in the sandbox environment, you can move out of the sandbox and into production. For more information, see
SMS message settings for Amazon Cognito user pools in the
Amazon Cognito Developer Guide.