The size of the file I downloaded is not the same size as the file I uploaded.

The most likely reason that the size of the file downloaded doesn't match what you uploaded is because the uploader will resize images automatically. If that's not the issue, the next most probable answer is that the uploaded file was sent incorrectly or that the file is corrupt.

As of October, 2005, Sprint and Nextel merged. Some of the gateways are now recompressing images to make them transmit faster to phones. If you are getting a size mismatched error on an image that you are trying to download as a wallpaper, you must add the HTTP Cache-control header "no-transform". This is a server-based fix, and search your web server documentation for how to add custom headers for files that are sent to mobile phones.