Phoner and PhonerLite

[kooliepup]

I have used Jitsi, Twinkle, SFLPhone, Ekiga, etc, and this is the one I prefer.
I was told about PhonerLite by my VOIP provider, who is also my ISP, and they use it for diagnosing customers' problems.

It is a WINE app, and also works on MS-Windows, if you must.

http://www.phonerlite.de/index_en.htm