Concept: Google Nexus Reversible (No up nor down)
No up nor down , the Phone can be used either way
To enable the reversible function, both "up" and "down" sides of the phone front face hosts a phone speaker that can be used during phone calls, otherwise the two speakers will act as a loud stereo speaker for movies,mp3,...etc.
Also both sides hosts front facing camera plus ambient light and proximity sensors, so basically we got double of everything in the front (except the display of course)
The 4 sides of the phone is touch sensitive, and changing the volume is done by a touch gestures in the side area, this way; you can control the volume in all orientations of the phone easily.