I'm trying to make the Pi act as a headless SIP client for conferencing. I'm using Debian/wheezy and linphonec.
For sound input I have a Griffin iMic (it also has an output socket), which plays back local audio files perfectly well - and works well for two-way audio on a laptop.
An echo test to the SIP server, using the iMic for input and output, gives about half a second of audio before it goes silent. There doesn't seem to be any error reported at either end - as far as linphone is concerned, the call keeps going, and nothing relevant shows up in dmesg.
Switching to the built-in audio output (keeping the iMic for input), I get unusably choppy and broken audio.
Is there anything I can do to fix this, other than hoping for better USB drivers?