/usr/pkgsrc/net/kphone (SIP fone) uses OSS compatibility mode calls to talk
to /dev/dsp.

for a (random?) selection of sip calls, under circumstances where its
toggling between call send and receive, it seems to want to re-open the
existing audio_fd.

I've tried commenting out the code which blocks if the fd is already open,
too early to say if that helped or not. 

Is this one of those EAGAIN type ioctl/emulation differences? The code
isn't very active, getting a non-OSS port may be hard.

-george