But it seems everyone loves to speculate and gossip on what's next for the iPhone so we did a side-by-side comparison of the iPhone and some competing, so-called "iPhone-killer" handsets, to get possible clues as to what changes Apple might be considering for its next iPhone.

And the biggest possible change could be in the screen. The iPhone's screen has been praised since Apple launched the phone in 2007.

"The iPhone offers an amazing resolution," said Macworld at the time, while Computerworld said: "It is the best screen you've ever seen on a device this small."

But at 480 pixels by 360 pixels the screen has remained the same while the rest of the cellular industry has moved forward. Today the Nokia N97 offers a higher 640x360 pixels resolution on a similar-sized 3.5-inch display while HTC's Touch HD and Toshiba's Japan-only T-01A both have 800x480 pixel resolution on screens that are 3.8-inches and 4.1-inches respectively.

Apple might not want to increase the screen size if it means making the iPhone larger but it's a good bet that a higher resolution display is set for the next model.