Hackers have succeeded in (partially) unlocking the iPhone so Apple's much-hyped device can be used on at least one network other than AT&T.

Although the iPhone Development Project team has broken the shackles tying the device and AT&T directly, there are still limitations that mean customers can use pre-paid SIMs from Cingular, for example, but not yet use any SIM of their choice.

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.

Using alternative SIMs provides several advantages. In the case of a Cingular SIM, there's no need to sign up to a new two-year contract. Those whose businesses subscribe to Cingular can use company SIMs on personally-bought iPhones. Finally, those not wishing to tie themselves to a contract can use pre-paid SIMs.

Hackers have been hard at work trying to unlock the functionality of the iPhone since the devices were released in the US earlier this month. Reverse engineer Jon Lech Johansen (DVD Jon) discovered a way to get iPod and Wi-Fi - though not the phone - features of the device working without signing up to AT&T within three days of its release.

The iPhone Development Project has taken the work further with an ambitious programme of goals, including the ability to unlock the phone (partially achieved with the development of IASign) and run third party applications on the device.

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.

Unconfirmed reports suggest an unnamed UK punter succeeded in getting an iPhone bought from eBay working on Vodafone's network, again using the iASign tool.

SIM numbers are network specific and users who've tried a similar trick in Germany and Canada have failed, so we're a bit skeptical that this is a genuine runner. ®

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