The whole building is teeming with iPhones. They're stacked in piles a dozen high, some wrapped in plastic, others held together by rubber bands. Just about every model is here, and they've arrive from places as far afield as the U.S., Japan, and Korea.
Dealers here declined to say where they get their old phones, but an electronics seller in neighboring Hong Kong said he buys used iPhones from the locals and sells them to shops in Shenzhen.
Some may also come from companies in the U.S. that specialize in buying old electronics. One such online business, Gazelle, said it has bought $180 million worth of used consumer gadgets, including iPhones.