X-Lite
Windows 2000/XP, Mac OS X
(download)
SJphone
Windows XPsp2/2000sp4, Pocket PC, Linux, MAC OS X
(download)
eyeBeam
Windows 2000/XP/Vista, Mac OS X
(download)
Ekiga
Windows, Linux
(download)
Express Talk
Windows 98/ME/2000/XP/2003/Vista, Mac OS X
(download)
PhonerLite
Windows
(download)
KPhone
Linux
(download)
Linphone
Linux, Windows, FreeBSD, OpenBSD
(download)
Twinkle
Linux
(download)
ZoIPer
Windows, Mac OS X, Linux
(download)
Fring
IPhone, Android, Nokia devices
(download)