If audio drivers for the modem or telephony device are not working properly, verify their installation by performing the following procedure:
From the Windows taskbar, click Start ... Settings ... Control Panel ... System.
Click the Device Manager tab and scroll down to Sound, video and game controllers. Expand the selection so that all sound, video and game controllers are visible.
Is the sound device for the modem or telephony card present? If not, look in a different location:
Have you found and enabled the audio drivers for the modem or telephony card? If not, they may need to be reinstalled. If the audio devices are still not visible after reinstallation, contact the manufacturer.
Does the sound device have an exclamation point or other icon through it? If so, the device may be conflicting with other devices. Have your systems professional evaluate the situation and leave it them to fix the error.
Note: Fixing configuration errors is not an easy task. Often it involves removing and/or reinstalling one or more devices. Sometimes devices have to be configured manually. In any case, we do not provide any instructions here because there is a real possibility of somehow ruining your system configuration while attempting to implement a fix. We suggest that if you are not confident about trying to fix device conflicts yourself, you should contact your system professional for assistance.
If the sound device is present and appears with a normal icon, then more than likely the audio drivers are installed properly.