Microsoft revealed Windows Phone Tango at MWC 2012 as a version of the operating system for low-cost devices with 256MB of RAM. The update was good news for owners of early Windows Phone devices that didn't meet the minimum requirements for Mango, but there have been a few hiccups. Microsoft said that not all apps in the Windows Phone Marketplace would work on devices with only 256MB of memory, and there have since been issues with Angry Birds and Skype, just to name a couple.