Unlike Android which relies on carriers to push updates to their devices (in the US at least), and allows for over the air updates directly through the phone using a data connection, Windows Phone requires you to connect your device to Zune in order to update. Here’s how you update your Lumia Device to the latest version available. This works for all Lumia phones, Lumia 610, Lumia 710, Lumia 800 and Lumia 900.
So here is the process:
1) Navigate the phone to the homescreen to the Settings option.
2) In the Settings option, find the About option and click on it.
3) Notice that under “More Information”, the current version of the Windows OS is displayed. There’s also an option for the phone to get notified whenever a new update is available under “Phone Update” in the Settings menu.
4) To check if there’s a new update available for your Lumia, connect the phone to the PC with the USB cord provided with the phone.
5) After the phone has been connected, run the Zune PC software. If this software hasn’t been installed yet, make sure that you install it before you plug in your Lumia device.
6) One this is done, the phone will be automatically detected by Zune. In some cases, the phone might go undetected. Check the USB cord and try using it on another USB port.
7) If there’s an update available, a pop-up screen would specify few essential changes, tweaks and modifications in the new version.
8) It should be noted that the Lumia device’s radio is switched off while updating, so the phone will not receive any messages or calls.
9) The phone automatically creates a backup of relevant data such as contacts and messages and stores them in the memory while you update it. Click on Update Now.
10) If the Lumia device has not been logged in on Zune, the software detects it as a guest phone.
11) Once you click Next, the update process will be initialized. Plug out the Lumia only after you get a notification by Zune, indicating that the update has been installed.