Even though China Unicom is the exclusive network provider for the iPhone, it still doesn't have complete control over the market. The company's new implementations are aimed at curbing speculative reselling of iPhones. Critics say it's a way to stop China Mobile, China Unicom's main competitor, from taking over the domestic market.

Under the previous agreement, customers who buy the iPhone package from Unicom receive the phone and a bundled SIM card. Users are locked to the China Unicom network for a period of 2 years. But on the gray market, some scalpers purchase iPhones and then resell the handset and cards separately at a high price. They're often even higher than the total value of the service bundle.

One internet seller said "Many people are buying them, some even buy dozens at one time."

China Mobile is another reason for China Unicom's new policies. 70 percent of iPhones in China use China Mobile's network. The operator has even launched a free SIM card cutting service, aiming to lure China Unicom's iPhone users.

Xiang Ligang, Secretary General of 3G Industry Alliance said "China Unicom planned to use the debut of the iPhone 4 to attract many high-end customers, but China Mobile has prevented those customers from signing up."

Many experts say the impact of China Unicom's new policy on potential customers is hard to predict. But there's no doubt - those who try to make a hefty profit by reselling iPhones, will be dismayed by the regulation.