A closer look, however, reveals that Microsoft's progress is still relatively muted, and that iOS is less vulnerable than it might appear.
Overall, IDC calculated that vendors shipped 236.4 million smartphones in Q2, up 51.3% from the 156.2 million units shipped during the same period last year. It also grew 9.3% relative to Q1 of 2013.
Most of the expansion was driven by Android, which accounted for almost four out of every five smartphones shipped during the quarter. Samsung, LG, Lenovo, Huawei and ZTE were the top vendors. Samsung led with 73.3 million units, or around two-fifths of the platform's total.
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Apple's iOS was second, with 13.2% of all smartphone shipments. The company shipped 5.1 million more iPhones than it did a year ago but nonetheless lost market share because the rest of the market gained users faster than iOS did.
Windows Phone increased its market share to 3.7%, up from 3.1% a year ago. It also shipped 77.5% more units -- the biggest upsurge in the market.
BlackBerry, meanwhile, continued to fade, with only 2.9% of shipments, down from 4.9% in Q2 of 2012. BlackBerry 10's much-hyped release hasn't slowed the company's decline, and Microsoft has now taken clear hold of the smartphone market's third position.
In a statement, IDC research manager Ramon Llamas linked iOS's decline to Apple's release cycle. Unlike Samsung, which IDC said benefited from the Galaxy S4 release, Apple has not debuted a new iPhone model since last fall, when the iPhone 5 hit the market.