there are a few distinct possible cases... If the underruns occur in the middle of a
voice transmission, you'd also expect to hear a "pop" in the audio. This
could suggest insufficient CPU. If they occur only at the end of transmissions I think
that's "normal" in the sense that the audio subsystem expects to receive a
continuous stream of samples and gives a little notification whenever they stop. It
would also be interesting to know how close the system is to being CPU-limited. Likewise,
it would be good to know more about the received signal quality - occasional loss of
signal lock could be another suspect...
Max