While we're on the topic of VoIP applications, I'm curious if anybody
has successfully combined Bluez's ALSA plugin with ALSA slave devices. 
There's a VoIP app that I'd like to use with my headset that only
supports a 32kHz sampling rate.  Because my bluetooth headset (using
"headset" profile) only supports an 8kHz sampling rate, I tried to use
an ALSA plugin for realtime rate conversion.  This ALSA plugin works
perfectly with my main soundcard (emu10k1), but fails with the bluetooth
device.

I have defined the ALSA plugin to use the bluetooth device:
pcm.bluetooth {
   type bluetooth
   device 00:16:8F:08:8F:80
   profile "auto"
}
pcm_slave.rate {
    pcm bluetooth
    format S16_LE
    channels 1
    rate 8000
}
pcm.complex_convert {
    type plug
    slave rate
}

ALSA doesn't seem to be the culprit, because defining the slave PCM with
"hw" as the master device instead of "bluetooth" will downsample any
incoming sound stream to 8kHz.  But when I try using the device with my
bluetooth device, e.g.:

$ aplay -D 44100.wav
Playing WAVE '44100.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono

The headset produces a buzzing noise (sounds like a 1kHz square wave),
and causes my system to hard lock a few seconds after aplay finishes. 
Is there a known compatibility issue between Bluez and ALSA plugins?  If
it's guaranteed to not work, would a sound daemon like Pulseaudio be a
decent compromise for realtime rate conversion?

Cheers,
Chip McArtor