This extension is compatible with “OpenCart SMS”.
Though you can use the built-in SMS feature, this is limited to SMS API using GET Method. Some SMS API uses the POST method. In such cases, you either contact support for integrating the SMS API (additional charges for this integration) to the extension or you can install “OpenCart SMS” which is designed to be compatible with SMS API using the GET or POST method. OpenCart SMS provides better debugging feature and SMS Log feature. Also, you can use several other SMS features of the extension.