This "everything or nothing" implementation suffers from a couple of problems. For one thing, it requires the press of a button every time you want to know some little detail like the battery status, the signal strength, or the time. Secondly, the glaring bright display can be jolting in the dark confines of someplace place like a movie theater.

Nokia has tried to work around this issue by displaying monochromatic status indicators on the display even with the backlight turned off in their earlier phones. However, since it didn't work in very dark or very bright lighting conditions, they've stopped using this method on more recent models.

Sony Ericsson deals with this by activating the backlight at a much lower brightness to display the status indicators when a button is pressed. This method works well for the most part, but it still does require that press of an extra button.

If a recent patent filing by Apple, the company details how status indication could be achieved on an iPhone without having to keep the display powered on the whole time or necessitating the press of a button. 

Credited to an Apple engineer by the name of Michael Rosenblatt, the patent describes , one stacked on top of the other. The light source immediately below the display would be the bright, primary one and would itself be placed over a low-powered source that emits very faint light.