Outbound Call Help

I am trying to create an outbound call however I only seem to be getting an empty array as a $_POST.

My PHP script is very simple:

<?php

echo "got here";

$my_file = 'file.txt';
$handle = fopen($my_file, 'w') or die('Cannot open file: '.$my_file);
$data = print_r($_POST, TRUE);
fwrite($handle, $data);

?>

When I trigger the workflow it creates the log file so SOMETHING is happening but the log only contains "array ( )"

I am telling clarizen to send all the information related to the current project.