Richard Fuchs writes:
In the third case, the audio stream was setup as a=sendonly, explaining the one-way audio. Probably caused by Firefox not being able to access the playback device.
as i reported in another message, i have also lately noticed in my tests that firefox sends invite with a=sendonly attribute. still don't know why, because the same firefox can play audio without problems using the html <audio> tag.
-- juha