From BBB

UNDER COSTRUCTION, PLEASE SEE THIS POST IN RESERVE COPY

This is a How-To guide on upgrading your Blackberry OS. This guide will also work for downgrading your OS, simply uninstall the previous OS from your PC, and install the lower version, then follow this guide, minus step 3.

First and foremost: You CAN load any carriers OS onto your Blackberry, regardless of what network you are on.

1. Make sure you have Desktop Manager installed on your computer. If you do not have this, you can download it here: http://na.blackberry.com/eng/services/desktop/

2. Open Desktop Manager and do a complete backup of your device, then close Desktop Manager.

3. Download and install the Blackberry OS from the carrier of your choice. Again, any carriers OS will work on your Blackberry. With that said, you CAN'T load an OS for another device/model to your Blackberry, so make sure you select the appropriate model. The following link is the official Blackberry list of carrier links for Blackberry software: http://na.blackberry.com/eng/support/downloads/download_sites.jsp

4. Delete the file called "Vendor.xml" located in C:\Program Files\Common Files\Research In Motion\Apploader . This will not affect your device or the OS is any way, except to allow the OS from another carrier on your device.

5. Plug in your Blackberry and open Device Manager. If it does not automatically detect the upgrade and prompt you to install, run the Application Loader, and it will install the updated files.

It is not uncommon for this process to take 45 minutes to an hour to complete. Your BlackBerry may restart 1 or 2 times durring this process. After the final restart you may see the spinning hourglass for 20 minutes, this is normal, do not unplug your BlackBerry.

Written / Created by: Nick Amsbaugh, Sr. Contributor