Google's Android is still the leading mobile operating system on Millennial Media's ad network, but Apple's iOS regained some lost ground in March thanks to the growth of the Verizon iPhone.
Rising by 11 percent since February, iOS captured 31 percent of all ad impressions on the network, according to Millennial Media's latest MobileMix report out today. That marked the first solid gain for iOS since it on the mobile network late last year.
Research In Motion also experienced a surge in growth for its mobile OS, growing by 29 percent to capture 18 percent of all ad impressions. Millennial Media attributed the gain to the rising popularity of RIM's BlackBerry Torch. Nokia's Symbian and Microsoft's Windows Phone remained flat, each hanging on to a 1 percent share.
Among mobile devices, the Verizon iPhone helped Apple retain its commanding lead as a hardware manufacturer with 32 percent of all mobile ad impressions on Millennial Media's network. That number marked a 14 percent increase since February and included the iPhone, iPad, and iPod Touch collectively. But the iPhone alone saw its popularity on the network rise by 17 percent.
Among Android device makers, Samsung kept its second place spot for the second consecutive month with 15.2 percent of all ad impressions. Samsung had a total of four handsets in the Top 20 Mobile Phone list--the Epic, the Vibrant, the Fascinate, and the Freeform.
In third place was HTC with a 10.69 percent share and six phones on the Top 20 list, including the Evo in third place with 3 percent of all impressions among mobile phones. RIM followed closely in fourth place with a 10.62 percent share. With 5.3 percent of all ad impressions, the BlackBerry Curve took the No. 2 spot just behind the iPhone.
Overall, smartphones accounted for 64 percent of all the ad impressions tracked by Millennial Media. Feature phones grabbed 19 percent, while connected devices, such as the iPad and iPod Touch, scooped up 17 percent.