Aruba Networks PowerConnect W Clearpass 100 Software Deployment Manual page 303

In the SMS Gateway field, if you choose Custom HTTP Handler from the drop-down list, you may
specify the HTTP method to use. The form displays the configuration options for that gateway type, and the
Service Method row includes the GET and POST options. When you select the POST option, the HTTP
Headers and HTTP Post rows are added. You can use the text fields in these rows to override HTTP headers
and enter the text to post.
If needed for custom SMS handlers, you can specify that the message format should be converted to hex-
encoded UTF-16 (Unicode).
ClearPass Guest 3.9 | Deployment Guide Guest Management | 303