In order to check that the API is working, if you enter the following URL into a web browser it will cause a text to be sent. Note that you should replace "<username>", "<password>" and "<mobile number>" with appropriate values.
http://www.totext.net/
selfcare/com/zipzaptext/selfcare/SendMessagesApi.action?
username=<username>
&password=<password>
&destination=<mobile number>
&message=This%20is%20a%20test