Plantronics DSP-400 USB Headset on a HP Pavilion zv6000 laptop

[Robert Goley <ragoley@rdasys.com>]

I have been trying to get the xten softphone working with broadvoice
under linux.  I have the application working but now I am having issues
with sound under linux.  The laptops sound card will work but breaks up
terribly.  This is not during actual calls.  It can not be blamed on
broadvoice.  this happens just when it is playing the beep like you are
dialing (before you press send).  I say a recommendation by xten support
that they tested using the Plantronics DSP-400.  The system recognizes
the device but no sound comes out.  It does not seem to be muted in
alsamixer or on the device itself.  Has anyone dealt with this before?
Any ideas for usb audio headsets?

Robert