Sorry if this has been posted as a solution already...I just stumbled onto this myself and wanted to share as I know it's been a frustration for many.... With numerous threads regarding the inability to open voicemail .wav attachments sent from corporate (and other) voice servers, I wanted to share my discovery/solution. It involves the purchase of the "Remote Wave" app from the Android Market, but requires one important step that I was previously overlooking. Someone had suggested downloading Remote Wave, as it was apparently developed for this specific purpose, but like most I found that even with it loaded on my Droid, I was never given the opportunity to open the voicemail .wav attachment with anything other than the native media player. My voicemails are sent to me through my corporate email and if I clicked on "open" it would open the native media player then tell me that the player could not play that file type. Here's how I got mine to work.....I forwarded one of my emails with the voicemail .wav file to my GMail email address. It has been noted that GMail will ask you which player you wish to open the file with, unlike the other (non-GMail) email app. Once you forward the voicemail, go ahead and select "preview" (only choice) which will open the file in GMail, then it will ask you which player you wish to open with. Before selecting Remote Wave, note below that there is a check box to check that says to use this as the default each time....CHECK THE DEFAULT BOX, THEN SELECT REMOTE WAVE. Your message will then go ahead and play from Remote Wave, but more importantly....YOU HAVE MADE REMOTE WAVE THE DEFAULT FOR THIS ACTION IN EITHER MAIL APPLICATION!!!! Now go back to your other email (in my case my corporate email) and open your voicemail attachment as you have been trying to do previously....YOU WILL NOW BE ABLE TO LISTEN TO YOUR VOICEMAIL IN REMOTE WAVE JUST LIKE YOU COULD IN GMAIL!!! I hope that this works the way it did for me, but I'm sure there are certain situations where it won't .....Good Luck!!