We have made an OSX build of Asterisk, the open source PBX and telephony server available as an OSX install package.
We are also developing Cocoa based GUI tools for configuration and management of Asterisk on MacOSX. A pre-release of the first GUI tool is now available.
For more information and download links check out the Asterisk Wiki …
All open source under the GPL!
Sunrise Telephone Systems Ltd.