How to check if your system has a MODEM WAVE driver installed?
 

If your modem supports VOICE, then a modem wave driver must be listed in the Windows Device Driver Manager.

Windows 9x/Me Windows 2000/XP  
  1. Open the Windows Control Panel
  2. Double click on the System Icon
  3. Click the Device Manager TAB
  4. Click the + next to Sound, video and game controllers.
  1. Open the Windows Control Panel
  2. Double click on the System Icon
  3. Click the Hardware TAB and Device Manager button
  4. Click the + next to Sound, video and game controllers.
  
Check if the "Wave Device for Voice Modem" driver appears. Check if the "UniModem Half-Duplex Audio Device" driver appears.