For the 3 months ending August 2013, the iPhone 5 remained the top-selling smartphone at T-Mobile, with 17.1% of sales. The study states that "When iOS first debuted on T-Mobile in mid-April, the majority of sales came from consumers upgrading from a feature phone to their first smartphone. However, looking at those who purchased an iPhone in the August period, 56% of those consumers came from another smartphone, including 38.5% from an Android device."

The study noted in general that in smartphone sales, Android has retained its lead for the 3 month period ending August 2013, with a 55.1% sales share of the smartphone market. Apple's iOS follows with 39.3% sale share, an increase of 5.4% versus the same period a year ago. Little movement is seen among the other operating systems in the market. Windows saw 3.0% of sales in the August period.

With Apple's iOS growing to 39.3% in Q3, one can only imagine where iOS will be when Mobile China comes on board in the coming months ahead. The expected leap could put iOS neck to neck against Android sometime in 2014.

In respect to the top wireless carriers, Verizon came out on top with a 37.1% share of smartphone sales in the 3 months ending August 2013 (seeing growth of 6.9% points). AT&T maintained second at 21.7%, and Sprint third with 14.6% of smartphone sales.

The data is derived from Kantar Worldpanel ComTech USA's consumer panel, which is the largest continuous consumer research mobile phone panel of its kind in the world, conducting more than 240,000 interviews per year in the U.S. alone.

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