Receiving WebAPI data in PHP – TROPO, INC.
When Tropo POSTs the WebAPI session or result object to your PHP web server, it will not appear in the $_POST superglobal variable. Post only contains name-value pairs when a service sends form-encoded data to your server, such as a form field and contents.
The WebAPI library handles this for you, but for those trying to process data without the library, this often trips developers up.