Linphone SIP software for Ubuntu Linux XP Vista and Mac : free VoIP video-phone

Linphone is an open source free SIP softphone, video phone which works with major operating systems like Ubuntu Linux XP Vista and Mac and allow you to register multiple SIP accounts with single sip software.

Features of Linphone
SIP support with major codecs
Video codec support
Webcam support
Text support
Address book
STUN support
All Operating systems.
Call in and out support
Multiple SIP