In a statement last week, Apple said that it has moved some of its personnel away from its newest version of Mac OS X, Leopard, to the team working on the June launch of the iPhone, reports Business Week.

Various iPhone suppliers have been told that the iPhone may not be available until the end of June, and Apple is stated as saying the iPhone "contains the most sophisticated software ever shipped on a mobile device," which hints at problems stemming from the complexity of the device.

Apple hopes customers will use iPhone for online purchases, so Apple must be sure the phone is not prone to hacker attacks. "They don't want it to be a version 1.0 of the iPhone, but version 4.9," Richard Doherty of Envisioneering Group said. "Apple wants to get it right the first time."

Another issue may come from the battery life. The phone will tout two batteries: one for the phone and the other for the music player. The phone battery would have to power a huge screen, Wi-Fi network connections, and many other power-hungry features.