There’s a Japanese restaurant in Boulder, CO that does something similar. There’s a little cube shaped dongle on the table and depending on the orientation it notifies the server of “I’m ready to order”, “Table service needed”, “check please”, etc. It worked surprising well.
Here’s a link if you’re ever visiting and want to check it out: https://goo.gl/maps/5tiXvJDC9DBXoHYt8