China Unicom (NYSE:

) has stopped taking orders on line due to such strong demand on pre-orders for Apple's (NASDAQ:

) iPhone 4, which have exceeded 200,000. About 60,000 buyers had received phones through China Unicom so far, the mobile operator said in a statement. By comparison, it took about six weeks to sell 100,000 iPhone 3GS handsets in 2009, according to

. The iPhone 4 is being offered through China Unicom with a two-year mobile subscription contract and also through Apple retail stores in China, which is currently the world's largest mobile phone market with more than 800 million subscribers.