The nation's second-largest wireless operator, China Unicom Sunday vowed to put an end to rogue sales of its bundled iPhone 4 packages by cutting the monthly rebate to users found involved in the practice.

The decision comes after the company got wind of shady online deals where consumers purchase iPhone 4 services and then sell off the parts — the phone and the two-year service subscription — separately for a profit, Wen Baoqiu, a spokesperson with China Unicom told the Global Times in a statement Sunday.

The iPhone 4, offered at a reduced rate through China Unicom on a two-year mobile subscription contract, includes a monthly rebate from the company if call limits are met.

Similar unauthorized transactions were growing in popularity Sunday, as demonstrated by a key word search on taobao.com, which revealed 428 search results offering "Iphone 4 service package" for sale. Target customers purchased their iPhone 4s from outlets other than China Unicom, and other smartphone owners that support 3G-services.

Tight market supplies are the main culprit behind this phenomenon, Ji Chendong, consultant for information communications and technologies with Frost and Sullivan China, told the Global Times Sunday.

The iPhone 4 is currently one of the top-selling smartphones on the market, and therefore in short supply. Official Apple store purchases of the device have recently required at least two-weeks for delivery. In addition to China Unicom's bundled iPhone 4 sales and Apple store sales, phones can also be obtained from the more expensive gray market.

The rogue sales have also proven to be good news for buyers of the service. Buyers that pay 600 yuan ($90.36) for the unauthorized two-year service package plus monthly 41 yuan ($6.17) to meet 286 yuan ($43.07) contracted price, get 900 minutes of free calls from China Unicom worth 245 yuan ($36.90), plus access to the Internet via non-iPhone 4 mobile phones.

"We haven't heard about this new rules yet," said an online vendor selling China Unicom's bundled service separate from the iPhone 4 on taobao.com. While declining to reveal her name, the woman claimed she would discontinue this type of sales if the China Unicom news proves to be true.

Cooperation with Apple Inc has helped China Unicom to steal away a 4 to 5 percent market share of the middle to high-end market from China Mobile, whose market share is about 70 to 75 percent, according to Ji of Frost and Sullivan China.