If Windows Media Player is not able to play the sound file (features=>sound files) in your Press8 Control Panel, then your version of Windows will require a Codec pack from MediaCodec.org who provide the Windows Essential Codec Pack for free download.
Please navigate to http://www.mediacodec.org/WECPSetup.exe to install this Codec pack which will resolve this problem with your Windows Media Player.
Clicking on the link above will download the necessary file to your computer. If you are given a choice of where to save the file, then save the file to your desktop.
Go to the location where the file was downloaded (desktop if so chosen) and click on the file. A security warning will ask to confirm your intention to run this file, and select "run".
The program will then install this codec pack after you agree to the software license agreement.
Next your will be asked to select the components to install. You may just click 'next' here, or for advanced users, make sure to at least select all the components related to Windows.
Confirm the destination folder location by clicking 'Install'.
If the install process detects and invalid codec, then give the program the permission to remove it.
If your Direct X Runtime needs updating, then this process will begin now, so please confirm the install or update.
Windows Media Player should now work for those Voice Mail Greeting Files.