The Click 2 Dial addon:
It will convert the phone numbers on the webpages opened in your browser to clickable links.
Clicking on such a link will start Zoiper and it will dial the number.
Click 2 Dial is a BIZ feature. It is not available for Zoiper 3 Free
Supported operating systems:
Windows - more information
Mac - more information
Linux - Click2Dial is currently not supported for Linux
More about Click2Dial