Dunno 'bout the 7650, but the 7210 does not seem to recognize the arrow keys as being mapped to Canvas.UP, DOWN, etc. Turns out the Canvas.UP is the '2' phone pad key. The Canvas.DOWN is the '8' phone pad key.
However, if you read the explicit key values instead of Canvas.UP, etc, you can actually trap the up, down, left, right arrow keys as follows, at least on the 7210 this is true:
up = -1
down = -2
left = -3
right = -4