The iPhone 4S was a big seller in the fourth quarter among U.S. purchasers of smartphones.
In a December survey conducted by Nielsen, nearly half of respondents (44.5 percent) who purchased a device within the previous three months selected Apple's new device. That's up from 25.1 percent in an October survey.
The increased demand for the iPhone is hardly surprising since Apple and its authorized carriers, including AT&T, Sprint Nextel and Verizon Wireless, began selling the iPhone 4S in October. The smartphone features the widely advertised Siri, an intelligent personal assistant that can recognize natural speech.
In spite of the popularity of the iPhone 4S, the leading smartphone platform remains Google's Android operating system, which is incorporated in jazzy phones manufactured by the likes of Motorola Mobility and Samsung. Of the smartphone owners surveyed by Nielsen in the fourth quarter, 46.3 percent carry an Android-based phone.
Nearly a third (30 percent) of respondents own a phone that incorporates iOS, the platform that runs Apple's line of iPhones. Another 14.9 percent own a BlackBerry, according to the Nielsen survey.