Client Diary has a great tool for checking your SMS usage. This is handy not just for operators with one site but with multiple sites it’s very handy to handle individual SMS billing to those sites.
IMPORTANT NOTE on statistics: The system has only been gathering statistics since Thursday, 14th of December 2017. Any dates before that will show no data.
IMPORTANT NOTE on Security settings: It’s important to note that you must give an employee permission to use this tool. See this article on security setup to learn more about that topic.