Windows Phone is going to enter a whole new market when it releases devices designed for the developing world and the prepaid market. For example, the Nokia Lumia 610 sports an 800Mhz processor and 256MB RAM, which was previously impossible on the platform.
As a result of this, Microsoft is limiting devices with 256MB RAM in a number of ways, in order to ensure a consistent experience among handsets:
1) Windows Phone app restrictions – Though 95% of apps will work with phones running less than 512MB RAM, some will not. This will be obvious when viewing the app in the Marketplace
2) Bing Local Scout, which was added to Mango devices, is not available on Tango devices running 256MB RAM
3) Podcast subscriptions and video podcasts will not be available
4) Fast app switching is nowhere to be found on these devices
5) SkyDrive photo upload is disabled
6) HD video playback is nowhere to be found
7) Background agents, such as the ability to update an app without it being open, is disabled
However, there are a few additions being made to Tango: improved SIM card maintenance, improved roaming settings, a new location alert icon (like in Android and iOS), and better MMS capabilities including video messages.
While all Windows Phone devices will eventually be upgraded to Tango, it won’t take place until Q2 after the first devices with 256MB RAM have been launched.