It’s working in Chrome for OSX, but it’s not in Chrome for Android 5.1.1. The code is:
[x_icon type="phone"] <i href="tel:45886" class="fa fa-whatsapp" aria-hidden="true" style="color: #25d366;"></i> <a href="tel:45886"> 666666 </a> (Mario)
This is showed in mobile: [x_icon type="phone"]
But this is not showed in mobile: <i href="tel:45886" class="fa fa-whatsapp" aria-hidden="true" style="color: #25d366;"></i>
Web: edinventa.com (the code is at the button; realise you must resize the window to a very small size to see it working: it is only shown in small screens as it has been though for mobile only)