Nokia has announced that it has started the rollout of the Window Portico Update for Lumia 920 and Lumia 820. The software update that brings a number of enhancements initially to the Nokia Lumia 920 and Lumia 820 at AT&T in the United States and to the Lumia 920 at Rogers in Canada.

The software update will be processed over-the-air (OTA) via a Wi-Fi connection. The Windows Phone 8 Portico update brings the following features to the Lumia 920 and Lumia 820.

• Enhancements in Messaging
• More efficient and reliable Bluetooth connectivity
• More efficient and reliable start-up sequence
• Enhancements in imaging performance and battery management
• Additional platform updates and enhancements

For Manual Update go to Settings -> Phone Update -> Check for Updates.

• If Wi-Fi is not on prior to checking for updates, select dismiss and turn on Wi-Fi.  (If Wi-Fi is on, this notice will not appear and the phone will begin downloading the update.)
• Phone will download updates and prepare to install. 
• Update is ready to install. Select Install.
• Wait as the update installs.    
• Update is all done. Select Done.
• Restart your phone.
• In Settings > About, confirm Software Version is now 1232.5951.1249.0001

The updating process will take 30 minutes. Nokia says that the other market owners of Lumia 820 and Lumia 920 will get update in early February 2013.