In the report, NPD Group, a wireless market research firm, said carrier defectors made the leap from June through August 2008. The iPhone 3G was released in mid-July. The AT&T boom surpassed industry standards, which saw just 23 percent of consumers, on average, switch carriers in the same time period.

NPD Group estimated that 47 percent of new AT&T iPhone users that switched came from Verizon Wireless, while another 24 percent left T-Mobile and 19 percent jumped from Sprint.

"The launch of the lower-priced iPhone 3G was a boon to overall consumer smart phone sales," said NPD Group director of industry analysis Ross Rubin in a statement. "While the original iPhone also helped win customers for AT&T, the faster network speeds of the iPhone 3G has proven more appealing to customers that already had access to a 3G network."

The launch of Apple's latest generation iPhone also boosted the device's clout in the consumer smart phone market. Before the 3G, iPhone sales accounted for 11 percent of the consumer market for smart phones, while after the 3G model's launch, Apple propelled to 17 percent of the market.

That jump in market share helped make the Apple iPhone 3G the top-selling consumer smart phone from June to August. The iPhone 3G was followed by Research In Motion (RIM) Ltd.'s BlackBerry Curve, the BlackBerry Pearl and the Palm Centro.

NPD Group's report also found that average smart phone prices are on the decline. Between June and August 2008, the average smart phone ran $174, a 26 percent drop from the same period last year, when the average smart phone had a price tag of $236.