public link: http://appery.io/app/mobile-frame?src...
scroll down to the button 'Text Messaging'. It will take to a page similar to the one in the tutorial I mentioned above.
Type the number and the message, and in the browser console you'll get the error message codeFailed to load resource: the server responded with a status of 400 (Bad Request)/code
I tested in the browser chrome and Appery tester.