The phones will still require a two-year supplier subscription, and are guaranteed free of scratches or dents. They are also covered by Apple's one-year warranty.
The provenance of the phones is unclear, although it is believed that many are returns from those who bought large numbers with a view to selling them on eBay.
Another source could be from Apple staff who declined their free iPhone and handed it back. A few of the handsets may also be returns that came back with faults and had to be rebuilt.
Apple chief executive Steve Jobs has said that he wants to sell a million iPhones by the end of September, but initial sales have been below expectations.
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