使用Amazon SNS发送短信

Question

I am trying to send SMS through the AWS SNS using the SDK for php.

I already configure the user in IAM (created a user to do this), grant full access to SNS service and check the keys many many times.

I am using the code that was posted in this topic for testing link and receiving this message error

Fatal error: Uncaught exception 'Aws\Sns\Exception\SnsException' with message 'Error executing "Publish" on "https://sns.us-east-1.amazonaws.com"; AWS HTTP error: Client error: POST https://sns.us-east-1.amazonaws.com resulted in a 403 Forbidden response: Sender SignatureDo (truncated...) SignatureDoesNotMatch (client): The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details

Anyone knows what I am doing wrong? I am not able to find the solution