Analyst firm iSuppli reported that the iPhone accounted for 1.8 per cent of all mobile handset unit sales to US consumers during July.
Most iPhone purchasers were male, 35 years or younger and possessed a four-year college degree or more.
Strong early consumer uptake conforms with iSuppli's forecast of 4.5 million iPhones shipping in 2007, rising to more than 30 million units in 2011.
ISuppli's US Consumer Panel Survey revealed that the two iPhone models now on the market outsold all smartphones in July.
ISuppli classifies the iPhone as a crossover phone with attributes that put it in competition with smartphones and feature phones.
While the iPhone has some features associated with smartphones, users cannot load third-party software onto the product, which is a key requirement to qualify for smartphone status.
ISuppli defines feature phones as handsets that have "rich functionality".
"This is a remarkable accomplishment for Apple, considering that July marked the first full month of sales for the iPhone," the market research firm stated.
"While iSuppli has not collected historical information on this topic, it is likely that the speed of the iPhone's rise to competitive dominance in its segment is unprecedented in the history of the mobile-handset market."
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