It just does nothing on tablet and desk, but works on phone.
I have VOIP on the desktop, and apps can call it, and I have call over lan on the tablet. I could also have my VOIP app active on the tablet.
Hi Joe, the click-to-call button is really meant for mobile. I get what you are saying, but that's the real purpose behind it. On desktop and tablet, I believe it just clicks and displays the phone number. I usually do not display that button on desktop or tablet devices as 'most' people do not make calls from their computers or tablets.
The click to call is specifically for phones.
If you want the button to open up special apps and use VOIP you need a custom widget.