Apple has published details concerning how existing iPhone users can claim their $100 rebate on the device, following its recent price cut.

Apple this month discontinued the 4GB iPhone model and reduced the price of the 8GB iPhone by $200, to $399.

Apple CEO Steve Jobs then published an open letter in which the company agreed to split the difference with existing iPhone customers as a good faith gesture.

However, the rebate isn't a cash lump sum - the company is simply offering customers $100 credit for anything they may in future buy from the Apple Store (online or retail).

To qualify for the $100 credit a customer's iPhone must be activated with AT&T and must have been purchased before 22 August. The application process is handled online, though confirmation is sent as a text message to an iPhone.

Requests for the credit must be submitted before 30 November, 2007.