AWS End User Messaging (PinPoint) Sandbox German Destination Number

The issue you're facing is due to the limitations of the AWS Pinpoint Sandbox mode.

The AWS Pinpoint Sandbox is designed to allow you to test the messaging functionality in a controlled environment, but it has some restrictions, including the use of only US-based phone numbers.

Unfortunately, it appears that you are not able to use a German phone number as the destination number when testing in the Sandbox mode. The error message "INVALID_IDENTITY_FOR_DESTINATION_COUNTRY" suggests that AWS Pinpoint is not able to validate the German phone number in the Sandbox environment.

To test AWS End User Messaging with a German phone number, you will need to move your account out of the Sandbox mode and into the Production environment. This will allow you to use non-US phone numbers, including German numbers, as both the originator and destination.

Keep in mind that when you move out of the Sandbox, you'll need to ensure that you've properly configured your AWS Pinpoint settings, including any necessary permissions, IAM roles, and message templates, to comply with the production environment requirements.