I’ve been experimenting with the Jitsi XMPP+SIP client on Linux and was having trouble with the audio settings, particularly for SIP.
Jitsi is a pretty versatile multi-protocol client written in Java. It runs on both Windows and Linux, and allows the use of both voice and video over SIP and XMPP when supported by the backend server.
I found the default settings for audio to be atrocious. Audio input quality was actually painful. After some research I found the following fairly minimla settings to work well.
1. In Options… Audio… Devices… Audio System. Set to PortAudio with Audio In, Audio Out and Notifications set to default.
2. In each account object I also changed
a. Connection… Keep Alive Method to REGISTER.
b. Connection… DTMF Method to RTP (RFC2833).
c. Encodings… remove all except PCMU/8000 and telephone-event/8000.