What causes the external speaker not to work for the modem speaker?

[cc]

The speaker of modem works. But it seems that my external speaker has some
problem with the sound of modem though it works
well for all media player applications in my OS.

What *service* in xp is related to the sound performance?

 

[Guest]

The settings can be located in Control Panel --> 'Sound & Audio Devices'.
For more disgnostic utility to test the sound, activate DirectX Diagnostic
tools. Click on 'Start' --> 'Run' --> type 'dxdiag'
If there isn't any sound, check connection and reinstall driver again.