Despite heavy competition from Android and upcoming Windows Phones, Apple's iPhone 4S remains the top selling smartphone in US for the month of March. Released nearly 6 months ago, the slight refresh of the original iPhone 4 was initially written off by critics as being a rehash of the old iPhone 4. However the sales figures beg to differ. According to the chart above, iPhone 4S has been the best selling smartphone on the top three carriers in the states; namely AT&T, T-Mobile and Verizon.

Next to the iPhone 4S is Samsung's current top Android offering Galaxy SII. Galaxy SII has been AT&T and T-Mobile's second best smartphone since December. It has been the top selling phone for Sprint, which currently does not offer any iPhones. Motorola Droid RAZR has enjoyed success and is at number 2 spot for Verizon. We only see a glimpse of Nokia in there however that might change with the launch of Lumia 900 for AT&T.