wengophone is an open source VoIP application.
wengophone for linux - latest packages
Does not work yet for my kubuntu 5.10, an unsolved dependency. There is a problem with making an account in Linux from the program, do it directly: https://www.openwengo.com/support/forum/viewtopic.php?t=15
I’m excited and eager to try it. 
For our french internet fiesta, I should talk with David Bitton (ceo wengo) tuesday night during a radioshow. If you have any specific questions like integrating a telepresence signal directly connected to voice-ip beside our TelePresence, just let it know. On the other hand, I’m really satisfied of the voice-quality found on [[GTalk?]] is great quality 
Any impressions from users of WengoPhone?
Define external redirect: GTalk