Why so many buttons? It really only needs three. One for the Menu, one for Answer, and one for Hangup. Home is basically the same as Menu, or they could be used interchangeably.
Something like this, button wise? (It's not pretty since I don't have Photoshop, but you can see the layout of the buttons)
The back button could be added between the two call buttons and the call buttons would probably look better flush with the casing, rather than round, but I don't have enough skill to do it.
And the background was because I was bored. :P