Apple is now offering customers an option to trade in their old iPhone 4S for a gift card worth up to US$345, which can be used at the Apple Store, just in time for the release of its new-generation smartphone, the iPhone 5, according to international media reports.

The trade-in voucher will definitely be a boon for those who cannot wait to get their hands on the iPhone5, which is scheduled to be unveiled on Sept. 12 and shipped to stores on Sept. 21. Apple's website shows that the company's iPhone 4S has already been added into its "Reuse & Recycle" program.

After inputting information about the storage capacity, color, and current condition of their iPhone 4S on Apple's website, customers can see how much they will get for sending in their old phones. The company will pay for packaging and shipping, and in return, send them a gift card to the Apple Store after receiving the old device.

Other resellers have also allowed customers to sell back their old iPhone 4S devices. It was recently reported that for a 64GB iPhone 4S in good condition, Apple pays back US$345, while Amazon provides the highest amount at US$500.

Analysts say that the old handsets in good condition will be resold as second-hand products or marketed after being restored.

So far, Apple has remained tight-lipped about the iPhone 5's new features.