voicemail in inbox-no need to download the sound file

What class of service? Are you looking for something like Grandcentral but that attaches audio files of the voicemail to the email notifications?

http://www.gotvoice.com/
http://www.evoice.com/evoice/twa/page/homePage
http://www.spinvox.com/ - UK only I think, converts to text.

If you mean something for a corporate voice mail system many PBX vendors have options that include such things.

actually an email service,say i record a voice on comp and send as attachment to you,when you open your inbox you can play that
voice file directly in your inbox with a play button

You can record sound and send it with default software on your computer already. But the recipient won't necessarily have a "play button" on their inbox because you don't control their software experience and not many email readers have inbuilt media players.

There is software like "My Voice Email" that aims at making it a bit easier but what you are asking for doesn't make a lot of sense to me so I don't think I can help you much further.