AT&T has unveiled a lineup of new Windows Phone 7.5 “Mango” smartphones coming soon, and plans to upgrade existing Windows Phone 7 devices to Mango soon. With the additional devices, AT&T will have seven different Windows Phone 7 smartphones to choose from.

AT&T currently offers four different Windows Phone 7 models: HTC HD7S, HTC Surround, Samsung Focus, and LG Quantum. Now, AT&T is expanding that lineup with three new Windows Phone 7.5 “Mango” smartphones–the HTC Titan, Samsung Focus S, and Samsung Focus Flash.