processing sound on thin clients

[Phyo W. Soe]

Hi all,

I have a question concerning recording/playing sound on thin clients. I 
have an Edubuntu 6.10 server and thin clients configured to run 
PXE/LTSP. The thin client can boot and I can log into user accounts. 
Now, I would like to run VoIP and video conferencing applications on the 
thin client using a program like Ekiga. The Edubuntu server I am using 
doesn't have a sound card but the thin client has one.
When I run Ekiga, configured to work with a SIP server on the LAN, on 
the Edubuntu server, I can make calls to other VoIP phones in the LAN 
but I can't hear/speak as the Edubuntu server doesn't have a sound card. 
When I tried to run Ekiga on the thin client (in lts.conf, I chaged 
LOCALDEV=T, SOUND=T, DISABLE_ACCESS_CONTROL=T) I can make calls but 
cannot talk/listen. Although the thin client has a sound card, in 
Ekiga's list of Audio Devices, it says "No device found" for both Output 
and Input audio devices. But I could hear System sounds like Beep, LogIn 
and LogOut sounds on the thin client, although there is a cross next to 
the speaker icon on the upper task bar (next to the clock).

Then, I configured another computer with a sound card to act as an 
Edubuntu server and tried the same thing. I chose "auto detect" for 
audio input/output devices and it can play sounds normally. I can make 
VoIP calls from the server although there is a big delay and the 
incoming audio quality is really terrible. On the thin client, I can now 
adjust the volume. In Ekiga configuration, it lists some devices for 
audio input/output devices now. I can send and receive VoIP calls with 
some delay but I cannot speak/hear anything. Moreover, I cannot hear 
system sounds anymore.

So, basically it's like the thin client device doesn't exist for the 
Edubuntu server and it thinks all the hardware devices and software 
configurations are those of the server computer. Is there any way to 
configure the thin clients so that it can record/playback sounds 
independent of what the server is (no sound card/a different type of 
sound card). Enabling local applications might be a solution but I don't 
like having to configure for each application that needs to use sound. I 
just want to tell the server to use the sound cards on the thin clients 
for handling sound.

Any help will be really appreciated.

Thanks.