USE IPHONE WITH CINGULAR NOT AT&T PREPAID IPHONES

A tool called iASign will unlock the iPhone allowing it to be used with any Cingular or AT&T SIM with FULL functionality of the iPhone, avoiding the need to use the iPhone-specific SIM that comes with the device. Virtual network operator pre-paid SIMs also work, providing these operators piggy-back on AT&T's network.

Last year, the US copyright office ruled that it was legal for consumers to unlock their mobile phones in order to use them with other carriers, a decision AT&T and Apple may seek to contest, but one which gives hackers (and commercial firms) some leeway.