LOS ANGELES - A GROUP of software developers plans to start selling soon a programme that will allow iPhone owners to use the hugely popular device on cellphone systems around the world and not just with AT&T.

The developers would not give CNN their last names, saying 'we don't want to be hounded', but a test done with the software appeared to be a success.

Apple's iPhone, released in the United States two months ago, was engineered to operate for the first two years only on the AT&T system through an exclusive arrangement between Apple and AT&T. It has not yet been sold outside the US.

Los Angeles software consultant Brett Schulte, who is not affiliated with the developers, demonstrated the software for CNN at the weekend.

An iPhone that had the new software appeared to work on the T-Mobile system just seconds after he replaced the AT&T SIM card with a T-Mobile SIM card.

'It's completely software hacked,' he said.

Two members of the team of software hackers, who identified themselves only as 'John' and 'Liu', told CNN in a phone interview that a core group of six people on three continents worked to unlock the iPhone as a hobby.

They said they will start selling the software as soon as their online payment systems are ready. They are also waiting for more information from their lawyers.