Hi,
No there is no API for this. The reason for this is that you should let the user dictate whether their device is muted or not muted. You might think this is a limitation of the platform however you have to think of the scenairo where you install an app and then without your knowledge it mutes your device, then when you are expecting that important call, you aren't notified for it in the way you want (the ringtone would be muted).
Hope this helps.
Paul Diston