Softphones (and web)

So I’m looking for a softphone solution, and rather than spend a week trying out 50 different options, I wonder if any of you might know which have the features I’m looking for.

  • functions as an asterisk extension
  • works from behind a NAT’d firewall to reach asterisk server
  • click to dial (trigger a call with the softphone by clicking on a button in a webpage)
  • extra bonus: a website embeddable softphone