A set of images leaked claims to be of Windows Phone "Tango" update reveal new features, improvements and changes to the operating system including: automatic app updates via Zune, new country support, and the increase of pre-installed apps from 16 to 40.
Some new features introduced with the Tango update include exporting and managing contacts directly to the SIM. Roaming will also allow 3 new options, which are 'no', 'domestic' and 'international'.
The update will also allow users to make more than 1 attachment to one MMS message, which include sound, video and pictures.
WP7Forum, who posted the images also talk about the 256MB issue. These low end devices will not be able to install some applications, and will include some more restrictions such as live tiles not updating automatically.
Paul Thurrott on February 10 detailed that "Tango" will likely be called "Windows Phone 7.5.1." He said Tango will be optimized for lower RAM requirements, and will support low-end Windows Phone handsets with just 256 MB of RAM, half of the 512 MB that is more common today.
"Developers will be able to target Tango or Windows Phone 7.5 (Mango) going forward, or both, and users of the new low-end systems will basically be able to access a subset of the existing Windows Phone Marketplace apps selection. (That said, I'm also told that Tango users will be able to browse, but not download, incompatible apps….)"
In addition, certain "resource-intensive background tasks" on Tango handsets will be disabled, Thurrott said. Some more restrictions include podcasts not being manageable via the device, and that video streams lower than 4MBs and encoding of H.264 v2 will be supported.
The devices will only be allowed to ship with a 3 or more megapixel camera, and photos will not be uploaded to SkyDrive automatically.
Here are the screenshots: