It will always be a problem, it's just simple physics. The light from the sun will exceed the luminosity of the device, and drown it out. It doesn't matter what the device is, this will always be a problem.
The only thing you can really do, is try and position yourself in opposition to the sun. So say when you open the phone to look at the inside screen, you're holding it so that the back side is facing the sun.
Some day, someone may invent a whole new type of display technology that finds some clever way around this. Right now, I'd place my bets on work being done to put tiny little screens into contact lenses, which could also be put into things such as sunglasses. Of course maybe someone will crack the idea of a mid-air holographic display that doesn't require large sums of energy and is thus portable. Until that day however, we're left to deal with displays that are difficult to read in direct sunlight, and there's really nothing that can be done about it. Razr, iPhone, Voyager, or any other, it doesn't matter, you'll have the same problem.
I have an Razr and want to replace it with a phone that I can see the screen in sunlight. The Iphone seems to be accptable but I looking at options, hopefully cheaper