I've recently launched a free service to make WebRTC calls from a
browser to phones running Lumicall
Just dial a number in the browser and if the phone has Lumicall then it
will ring - nothing to pay. And the software is free too. The blog and
the Lumicall site have had a tenfold increase in traffic since this was
released.
I've explained it in more detail in my blog, any feedback would be very
welcome:
http://danielpocock.com/free-calling-from-browser-to-mobile