Blink, a state of the art, easy to use SIP client
http://icanblink.com
Blink is the best SIP client for Mac. You can use it with any SIP provider or its own fully-featured SIP service.
#Teleku , Teleku Launches!
http://teleku.tumblr.com/post/405877949/teleku-launches
"Teleku is a new cloud-based telecom company that allows Web developers to build and host phone applications that answer inbound calls and initiate outbound calls, interact with Web applications, and send/receive SMS text messages! Using simple XML responses in your HTTP Web pages, you can deliver sophisticated interactive voice response (IVR) telephony applications in as little as 5 minutes!"
BBC-Radio-Between-The-Ears.mp3 (audio/mpeg Object)
http://www.cosmictap.com/media/BBC-Radio-Between-The-Ears.mp3
telephone - Google Code
http://code.google.com/p/telephone
The Geek Gazette - Build Your Own PBX
http://geekgazette.com/index.php?Itemid=26&id=2&option=com_content&task=view
"What would it mean to you to have your own full-featured PBX system at your home or small office?"