If the iPhone 3G was enough impetus to get you to drop your wireless provider like it was hot, then this news probably won't surprise you. According to figures from market-research firm NPD Group, almost one-in-three iPhone 3G customers were defectors from other mobile operators. The report also says iPhone 3G also topped sales in the smartphone category.

NPD says 30% of iPhone 3G customers between June and August 2008 came from other providers, compared to an average of 23% of consumers who switched wireless service in the same period. Defectors from Verizon led the charge to the iPhone 3G, with 47% of those switchers; T-Mobile followed at 24% and Sprint grabbed the bronze at 19%.

The cause of all the churn? Ross Rubin, directory of industry analysis for NPD, said in a statement that the iPhone 3G's lower price and addition of 3G networking were major factors for those coming from other networks.

During the June through August period, the iPhone 3G was the top-seller in the smartphone category, beating out competition from RIM and Palm. According to NPD, the iPhone 3G has boosted the iPhone's market share from 11% before the new model's introduction to 17% as of the end of August.

Next stop: the 10 million mark. Apple's quarterly financial report is scheduled for Oct. 21, and will let us know how close the company is to hitting its self-imposed goal for iPhone sales in 2008.

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