The SIP Communicator is still under active development and its first real release approaches. In order to learn the exact status of the development you could check out the SIP Communicator Roadmap or join the announce mailing list. In the mean time you could try one of the following nightly builds.

SIP Communicator 1.0-alpha3 nightly builds

• Microsoft Windows installers
• Debian packages (you can also use our debian/ubuntu repository)
• Arch Linux packages
• Fedora RPM packages
• MAC OS X packages
• Source code snapshots
  
• All nightly builds

SIP Communicator 1.0-alpha2 release

• Microsoft Windows installer - sip-communicator-1.0-alpha2.exe
• Debian Package - sip-communicator_1.0-alpha2_i386.deb (or our debian repository)
• Fedora RPM package - sip-communicator-1.0-alpha2.i386.rpm
• Generic Linux Installer - sip-communicator-1.0-alpha2-linux.bin
• Mac OS X package - SIP Communicator-1.0-alpha2.dmg
• Generic installer for all OSs - sip-communicator-1.0-alpha2.jar
• Source code - sip-communicator-1.0-alpha2-src.zip
  

Note: We would like to support as many distribution specific packages as possible. If you would like to be a maintainer of such a package - please let us know