I have a Motorola Q and we use a Shoretel phone system, which forwards voicemails to Outlook as WAV files. I am not able to play them with the media player on the Q, but after I installed TCPMP and the wavpack, it works through using that player. Here is where I found those two packages...

http://picard.exceed.hu/tcpmp/test/

I first installed "tcpmp.smartphone.0.72RC1.exe" and then "wavpack.plugin.0.72RC1.zip".

Hope that helps.