- Linux:
Twinkle (http://twinklephone.com)
Zoiper (http://zoiper.com)
Qutecom (http://sourceforge.net/projects/qutecom.mirror/)
- Mac:
Xlite/Eyebeam (http://counterpath.com)
Zoiper (http://zoiper.com)
- Windows:
Xlite/Eyebeam (http://counterpath.com)
Zoiper (http://zoiper.com)