Registered Sender ID not working in Pinpoint API

The issue you're experiencing with your registered Sender ID not working in the Pinpoint API, despite functioning correctly in the AWS End User Messaging SMS simulator, could be due to several factors:

1. Sender ID support varies by country: It's important to note that support for Sender IDs differs depending on the recipient's country. Some major markets, including the United States, Canada, and China, don't support Sender IDs. Ensure that the country you're sending to supports Sender ID authentication.

2. Resource policy configuration: With the introduction of AWS End User Messaging service, origination identities (including Sender IDs) now have resource policies that specify which entities can access them to send text messages. Check if you have the necessary permissions set up for Amazon Pinpoint to use the Sender ID.

3. Message-level Sender ID override: When sending individual messages, you can specify a Sender ID at the message level, which overrides the default Sender ID. Ensure you're not accidentally overriding your approved Sender ID in your API call.

4. Origination identity fallback: If a Sender ID is not specified or not supported in the recipient's country, Amazon Pinpoint may fall back to other origination identities. This could explain why you're seeing "Likely-SCAM" instead of your registered Sender ID.

5. API configuration: Double-check that your API call is correctly formatted and includes all necessary parameters, including the correct Sender ID.

To troubleshoot this issue:

1. Verify that the recipient's country supports Sender IDs.
2. Check the resource policy for your Sender ID and ensure it grants access to Amazon Pinpoint.
3. Review your API call to make sure the Sender ID is correctly specified.
4. Enable event logging for your Pinpoint project to get more detailed information about message delivery status.
5. Test with different recipient numbers to see if the issue is specific to certain destinations.

If the problem persists after these checks, you may need to contact AWS Support for further investigation, as they can access non-public information about your account and message delivery status.
Sources
Issue with Approved Sender ID Not Appearing in SMS Messages via Amazon SNS | AWS re:Post
Resolving Sender ID Display Issues with Amazon Pinpoint SMS in Bangladesh | AWS re:Post
Origination identities for Amazon SNS SMS messages - Amazon Simple Notification Service

the below policy is already granted to the iam user making the api call { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": "mobiletargeting:SendMessages", "Resource": "arn:aws:mobiletargeting:ap-southeast-1:<accountid>:apps/<appid>" } ] }