While many of the latest Apple devices are running iOS 7, you can still update your iPhone 2G to iOS 5 to get a good variety of updated features such as wireless iTunes syncing, iCloud backups, Notification Center, and Twitter integration. Whited00r software is a custom made iOS that allows you to upgrade and get the additional features that iOS 5 has that you wouldn’t have been able to get otherwise.
Whited00r software is safe to install and has a version for locked iPhone 2 G versions and unlocked ones as well. It is also easy to uninstall if you don’t like the upgrade. Most people who are using it though enjoy having all the additional features that this software provides.
Source OSX Daily