Using Twinkle for VoIP27 Apr 2010
Configuring the user
Enter your user details. Note that the SIP password is different from the password to log in on the VoIPTalk website. Log in on the VoIPTalk website and click on VoIPtalk ID to view VoIPtalk (SIP) password.
Alternatively you can set up port forwarding on your router. Then you don't need to specify a STUN server. In any case make sure that your firewall doesn't block SIP traffic. You can call sip:email@example.com in order to test whether the configuration works.
I recommend using G.711 u-law as preferred audio codec.
In Kubuntu 10.04 you have to set all audio devices (input, output, and ringtone) to ALSA/Default.
There is a freeware VoIP client for Microsoft Windows called X-Lite.